Journal articles: 'HEMTs'

1

Lin, Yu-Shyan, and Shin-Fu Lin. "Large-Signal Linearity and High-Frequency Noise of Passivated AlGaN/GaN High-Electron Mobility Transistors." Micromachines 12, no. 1 (December 24, 2020): 7. http://dx.doi.org/10.3390/mi12010007.

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This study proposes AlGaN/GaN/silicon high-electron mobility transistors (HEMTs) grown by a metallorganic chemical vapor deposition (MOCVD) system. The large-signal linearity and high-frequency noise of HEMTs without and with different passivation layers are compared. The experimental data show that the addition of a TiO2 passivation layer to undoped AlGaN/GaN HEMT’s increases the value of the third-order intercept point (OIP3) by up to 70% at 2.4 GHz. Furthermore, the minimum noise figure (NFmin) of the HEMT with TiO2 passivation is significantly reduced.

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Lin, Yu-Shyan, and Chun-Cheng Lin. "AlGaAs/InGaAs High-Electron Mobility Transistors Fabricated Using Silicon Nitride Passivation and Selective-Etching Process." Science of Advanced Materials 13, no. 4 (April 1, 2021): 638–41. http://dx.doi.org/10.1166/sam.2021.3928.

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AlGaAs/InGaAs high-electron mobility transistors (HEMTs) are grown by molecular beam epitaxy (MBE). The studied HEMTs use two AlAs layers as etch-stop layers in the selective-etch recessed-gate fabrication of the HEMTs. The influence of passivation using silicon nitride on HEMTs is examined. Passivation improves the dc, high-frequency, and power characteristics of AlGaAs/InGaAs HEMTs. The passivated HEMT has a maximum extrinsic transconductance of 207 mS/mm, a unity-current-gain frequency (fT) of 13 GHz, and a maximum oscillation frequency (fmax) of 26 GHz. Furthermore, the variation of dc characteristics of the passivated HEMT with temperature is reduced.

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3

Wang, Chih Hao, Liang Yu Su, Finella Lee, and Jian Jang Huang. "Applications of GaN-Based High Electron Mobility Transistors in Large-Size Devices." Applied Mechanics and Materials 764-765 (May 2015): 486–90. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.486.

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We demonstrate a novel design of large-size device in AlGaN/GaN high-electron-mobility transistor (HEMT). Depletion mode (D-mode) HEMTs and enhancement mode (E-mode) HEMTs are fabricated in our research. The saturation current of D-mode HEMTs is over 6A. By using Cascode structure, the D-mode HEMT becomes a normally-off device efficiently, and the threshold voltage of it rises from-7V to 2V. By using BCB (Benzocyclobutene) as the passivation, the E-mode HEMT shows an excellent characteristic. Also, when the VGS of the E-mode HEMT is over 9V, it still shows a good performance.

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A. Revathy and C.S. Boopathi. "Ultra-wide Bandgap AlGaN Channel HEMTs for Portable Power Electronics Applications." International Journal of Nanoelectronics and Materials (IJNeaM) 16, no. 2 (October 22, 2024): 301–12. http://dx.doi.org/10.58915/ijneam.v16i2.1225.

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AlGaN channel (Eg>3.4 eV) is the most effective method for enhancing the breakdown field of the group III-nitride based HEMTs. This work demonstrates the potential of AlGaN double channel HEMTs on Silicon carbide substrate. The device DC characteristics are investigated using numerical simulator by using drift-diffusion transport model. The AlGaN double channel HEMTs enhances the total 2DEG density due to double potential well and shows better current driving capability (IDS) of 0.714 A/mm, transconductance (gm) of 116 mS/mm, and low specific ON-resistance (Ron) of 3.262 Ω.mm. The AlGaN double channel HEMT on Silicon carbide substrate exhibited 680 V blocking voltage (VBR) and gate field plate HEMT shows 532 V. The effective reduction in electric field at the gate edge is the major source for elevated breakdown voltage in field plate HEMTs. The superior DC characteristics indicates the proposed wide bandgap channel HEMT is suitable device for future portable power converters.

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5

Revathy, A., C. S. Boopathi, Osamah Ibrahim Khalaf, and Carlos Andrés Tavera Romero. "Investigation of AlGaN Channel HEMTs on β-Ga2O3 Substrate for High-Power Electronics." Electronics 11, no. 2 (January 12, 2022): 225. http://dx.doi.org/10.3390/electronics11020225.

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The wider bandgap AlGaN (Eg > 3.4 eV) channel-based high electron mobility transistors (HEMTs) are more effective for high voltage operation. High critical electric field and high saturation velocity are the major advantages of AlGaN channel HEMTs, which push the power electronics to a greater operating regime. In this article, we present the DC characteristics of 0.8 µm gate length (LG) and 1 µm gate-drain distance (LGD) AlGaN channel-based high electron mobility transistors (HEMTs) on ultra-wide bandgap β-Ga2O3 Substrate. The β-Ga2O3 substrate is cost-effective, available in large wafer size and has low lattice mismatch (0 to 2.4%) with AlGaN alloys compared to conventional SiC and Si substrates. A physics-based numerical simulation was performed to investigate the DC characteristics of the HEMTs. The proposed HEMT exhibits sheet charge density (ns) of 1.05 × 1013 cm−2, a peak on-state drain current (IDS) of 1.35 A/mm, DC transconductance (gm) of 277 mS/mm. The ultra-wide bandgap AlGaN channel HEMT on β-Ga2O3 substrate with conventional rectangular gate structure showed 244 V off-state breakdown voltage (VBR) and field plate gate device showed 350 V. The AlGaN channel HEMTs on β-Ga2O3 substrate showed an excellent performance in ION/IOFF and VBR. The high performance of the proposed HEMTs on β-Ga2O3 substrate is suitable for future portable power converters, automotive, and avionics applications.

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Kim, Hyun-Seop, Myoung-Jin Kang, Jeong Jin Kim, Kwang-Seok Seo, and Ho-Young Cha. "Effects of Recessed-Gate Structure on AlGaN/GaN-on-SiC MIS-HEMTs with Thin AlOxNy MIS Gate." Materials 13, no. 7 (March 27, 2020): 1538. http://dx.doi.org/10.3390/ma13071538.

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This study investigated the effects of a thin aluminum oxynitride (AlOxNy) gate insulator on the electrical characteristics of AlGaN/GaN-on-SiC metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). The fabricated AlGaN/GaN-on-SiC MIS-HEMTs exhibited a significant reduction in gate leakage and off-state drain currents in comparison with the conventional Schottky-gate HEMTs, thus enhancing the breakdown voltage. The effects of gate recess were also investigated while using recessed MIS-HEMT configuration. The Johnson’s figures of merit (= fT × BVgd) for the fabricated MIS-HEMTs were found to be in the range of 5.57 to 10.76 THz·V, which is the state-of-the-art values for GaN-based HEMTs without a field plate. Various characterization methods were used to investigate the quality of the MIS and the recessed MIS interface.

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7

Wang, Yingnan, Xiufei Hu, Lei Ge, Zonghao Liu, Mingsheng Xu, Yan Peng, Bin Li, et al. "Research Progress in Capping Diamond Growth on GaN HEMT: A Review." Crystals 13, no. 3 (March 14, 2023): 500. http://dx.doi.org/10.3390/cryst13030500.

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With the increased power density of gallium nitride (GaN) high electron mobility transistors (HEMTs), effective cooling is required to eliminate the self-heating effect. Incorporating diamond into GaN HEMT is an alternative way to dissipate the heat generated from the active region. In this review, the four main approaches for the integration of diamond and GaN are briefly reviewed, including bonding the GaN wafer and diamond wafer together, depositing diamond as a heat-dissipation layer on the GaN epitaxial layer or HEMTs, and the epitaxial growth of GaN on the diamond substrate. Due to the large lattice mismatch and thermal mismatch, as well as the crystal structure differences between diamond and GaN, all above works face some problems and challenges. Moreover, the review is focused on the state-of-art of polycrystalline or nanocrystalline diamond (NCD) passivation layers on the topside of GaN HEMTs, including the nucleation and growth of the diamond on GaN HEMTs, structure and interface analysis, and thermal characterization, as well as electrical performance of GaN HEMTs after diamond film growth. Upon comparing three different nucleation methods of diamond on GaN, electrostatic seeding is the most commonly used pretreatment method to enhance the nucleation density. NCDs are usually grown at lower temperatures (600–800 °C) on GaN HEMTs, and the methods of “gate after growth” and selective area growth are emphasized. The influence of interface quality on the heat dissipation of capped diamond on GaN is analyzed. We consider that effectively reducing the thermal boundary resistance, improving the regional quality at the interface, and optimizing the stress–strain state are needed to improve the heat-spreading performance and stability of GaN HEMTs. NCD-capped GaN HEMTs exhibit more than a 20% lower operating temperature, and the current density is also improved, which shows good application potential. Furthermore, the existing problems and challenges have also been discussed. The nucleation and growth characteristics of diamond itself and the integration of diamond and GaN HEMT are discussed together, which can more completely explain the thermal diffusion effect of diamond for GaN HEMT and the corresponding technical problems.

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8

Koehler, Andrew D., Travis J. Anderson, Marko J. Tadjer, Tatyana I. Feygelson, Jennifer K. Hite, Karl D. Hobart, Bradford B. Pate, Francis J. Kub, and Charles R. Eddy. "Topside Nanocrystalline Diamond Integration on AlGaN/GaN HEMTs for High Temperature Operation." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, HITEC (January 1, 2014): 1–6. http://dx.doi.org/10.4071/hitec-tp17.

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GaN high electron mobility transistors (HEMTs) performance is limited by increased channel temperature, particularly resulting from self-heating during high power operation. Topside nanocrystalline diamond (NCD) layers have been integrated on AlGaN/GaN (HEMTs) to improve thermal management. HEMTs with NCD heat-spreading layers exhibit a 20% decrease in peak channel temperature compared to reference HEMTs, measured by Raman thermography, as well as improved sheet carrier density, transconductance, sheet resistance, Hall mobility, on-state resistance, and breakdown voltage. A “gate after diamond” approach is implemented to improve the thermal budget of the deposition process while maintaining the integrity of the Schottky gate electrode in a scalable process. Processing improvements for integrating NCD-capping with the HEMT are being pursued, such as eliminating the SiNx passivation interlayer, such that the NCD film is directly on the AlGaN barrier, as well as a sacrificial gate process. Also, boron doped p+-NCD films were implemented as gate electrodes for the AlGaN/GaN HEMT to place the heat-spreading layer in direct contact with the heat source, for a thermally stable heat-spreading gate contact.

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9

Wu, Nengtao, Zhiheng Xing, Shanjie Li, Ling Luo, Fanyi Zeng, and Guoqiang Li. "GaN-based power high-electron-mobility transistors on Si substrates: from materials to devices." Semiconductor Science and Technology 38, no. 6 (April 25, 2023): 063002. http://dx.doi.org/10.1088/1361-6641/acca9d.

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Abstract Conventional silicon (Si)-based power devices face physical limitations—such as switching speed and energy efficiency—which can make it difficult to meet the increasing demand for high-power, low-loss, and fast-switching-frequency power devices in power electronic converter systems. Gallium nitride (GaN) is an excellent candidate for next-generation power devices, capable of improving the conversion efficiency of power systems owing to its wide band gap, high mobility, and high electric breakdown field. Apart from their cost effectiveness, GaN-based power high-electron-mobility transistors (HEMTs) on Si substrates exhibit excellent properties—such as low ON-resistance and fast switching—and are used primarily in power electronic applications in the fields of consumer electronics, new energy vehicles, and rail transit, amongst others. During the past decade, GaN-on-Si power HEMTs have made major breakthroughs in the development of GaN-based materials and device fabrication. However, the fabrication of GaN-based HEMTs on Si substrates faces various problems—for example, large lattice and thermal mismatches, as well as ‘melt-back etching’ at high temperatures between GaN and Si, and buffer/surface trapping induced leakage current and current collapse. These problems can lead to difficulties in both material growth and device fabrication. In this review, we focused on the current status and progress of GaN-on-Si power HEMTs in terms of both materials and devices. For the materials, we discuss the epitaxial growth of both a complete multilayer HEMT structure, and each functional layer of a HEMT structure on a Si substrate. For the devices, breakthroughs in critical fabrication technology and the related performances of GaN-based power HEMTs are discussed, and the latest development in GaN-based HEMTs are summarised. Based on recent progress, we speculate on the prospects for further development of GaN-based power HEMTs on Si. This review provides a comprehensive understanding of GaN-based HEMTs on Si, aiming to highlight its development in the fields of microelectronics and integrated circuit technology.

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10

Lin, Yu-Shyan, and Heng-Wei Wang. "AlGaN/AlN/GaN Metal-Oxide-Semiconductor High-Electron Mobility Transistor with Annealed Al₂O₃ Gate Dielectric." Science of Advanced Materials 14, no. 8 (August 1, 2022): 1419–22. http://dx.doi.org/10.1166/sam.2022.4343.

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An AlGaN/AlN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMT) with an Al2O3 insulator is studied. The post-deposition annealing (PDA) of Al2O3 is conducted. The effects of PDA in an N2 atmosphere on the performance of the MOS-HEMTs are studied. Experimental results demonstrate that the trap density in the Al2O3 MOS diode is significantly decreased by annealing. Adding annealed Al2O3 as a surface passivation and a gate oxide layer on HEMTs reduces gate leakage currents, increases the two-terminal reverse breakdown voltage, and improves the high-frequency performance of the HEMTs.

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11

Lee, Ming-Wen, Cheng-Wei Chuang, Francisco Gamiz, Edward-Yi Chang, and Yueh-Chin Lin. "Improvement of AlGaN/GaN High-Electron-Mobility Transistor Radio Frequency Performance Using Ohmic Etching Patterns for Ka-Band Applications." Micromachines 15, no. 1 (December 30, 2023): 81. http://dx.doi.org/10.3390/mi15010081.

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In this paper, AlGaN/GaN high-electron-mobility transistors (HEMTs) with ohmic etching patterns (OEPs) “fabricated to improve device radio frequency (RF) performance for Ka-band applications” are reported. The fabricated AlGaN/GaN HEMTs with OEP structures were used to reduce the source and drain resistances (Rs and Rd) for RF performance improvements. Within the proposed study using 1 μm hole, 3 μm hole, 1 μm line, and 3 μm line OEP HEMTs with 2 × 25 μm gate widths, the small signal performance, large signal performance, and minimum noise figure (NFmin) with optimized values were measured for 1 μm line OEP HEMTs. The cut-off frequency (fT) and maximum oscillation frequency (fmax) value of the 1 μm line OEP device exhibited optimized values of 36.4 GHz and 158.29 GHz, respectively. The load–pull results show that the 1 μm line OEP HEMTs exhibited an optimized maximum output power density (Pout, max) of 1.94 W/mm at 28 GHz. The 1 μm line OEP HEMTs also exhibited an optimized NFmin of 1.75 dB at 28 GHz. The increase in the contact area between the ohmic metal and the AlGaN barrier layer was used to reduce the contact resistance of the OEP HEMTs, and the results show that the 1 μm line OEP HEMT could be fabricated, producing the best improvement in RF performance for Ka-band applications.

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12

Chen, Kun-Ming, Chuang-Ju Lin, Chia-Wei Chuang, Hsuan-Cheng Pai, Edward-Yi Chang, and Guo-Wei Huang. "Analysis of Trapping Effect on Large-Signal Characteristics of GaN HEMTs Using X-Parameters and UV Illumination." Micromachines 14, no. 5 (May 8, 2023): 1011. http://dx.doi.org/10.3390/mi14051011.

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GaN high-electron-mobility transistors (HEMTs) have attracted widespread attention for high-power microwave applications, owing to their superior properties. However, the charge trapping effect has limitations to its performance. To study the trapping effect on the device large-signal behavior, AlGaN/GaN HEMTs and metal-insulator-semiconductor HEMTs (MIS-HEMTs) were characterized through X-parameter measurements under ultraviolet (UV) illumination. For HEMTs without passivation, the magnitude of the large-signal output wave (X21FB) and small-signal forward gain (X2111S) at fundamental frequency increased, whereas the large-signal second harmonic output wave (X22FB) decreased when the device was exposed to UV light, resulting from the photoconductive effect and suppression of buffer-related trapping. For MIS-HEMTs with SiN passivation, much higher X21FB and X2111S have been obtained compared with HEMTs. It suggests that better RF power performance can be achieved by removing the surface state. Moreover, the X-parameters of the MIS-HEMT are less dependent on UV light, since the light-induced performance enhancement is offset by excess traps in the SiN layer excited by UV light. The radio frequency (RF) power parameters and signal waveforms were further obtained based on the X-parameter model. The variation of RF current gain and distortion with light was consistent with the measurement results of X-parameters. Therefore, the trap number in the AlGaN surface, GaN buffer, and SiN layer must be minimized for a good large-signal performance of AlGaN/GaN transistors.

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13

Kim, Bonghwan, and Seung-Hwan Park. "Hybrid High-Power AlGaN/CdZnO/GaN/AlGaN HEMT with High Breakdown Voltage." Materials 17, no. 22 (November 14, 2024): 5560. http://dx.doi.org/10.3390/ma17225560.

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This study investigates the effects of incorporating a CdZnO layer in place of the conventional InGaN layer in an AlGaN/InGaN/GaN/AlGaN/SiC high-electron mobility transistor (HEMT) structure. We examine the resulting characteristics and assess the potential of high-power HEMT applications, including high-power switching converters, through simulation analysis. Both structures demonstrate increased drain current and transconductance with increasing Al content in the barrier layer. However, HEMTs with a CdZnO layer exhibit higher drain current compared to those with an InGaN layer at the same Al content. The breakdown voltage decreases rapidly with increasing Al content, attributed to changes in electric field distribution. HEMTs with a CdZnO/GaN channel exhibit a slightly higher breakdown voltage (~795 V) compared to those with an InGaN/GaN channel (~768 V) at a lower Al content of x = 0.10. These results suggest that CdZnO-based HEMTs have significant potential for high-power, high-frequency applications.

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14

Guan, Wuxiao. "Advancements and trends in GaN HEMT." Applied and Computational Engineering 23, no. 1 (November 7, 2023): 245–51. http://dx.doi.org/10.54254/2755-2721/23/20230662.

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Gallium Nitride based High Electron Mobility Transistors (GaN HEMTs) technology has made significant advancements, revolutionizing the field of power electronics. With their unique properties such as high breakdown voltage, high frequency, and high electron mobility and high-power capabilities, GaN HEMTs offer significant advantages over traditional silicon-based devices, such as improved power density, higher operating temperature, and enhanced reliability. GaN HEMTs have shown great potential in sensing applications, such as gas and biosensors. This thesis explores the advancements and trends in GaN HEMT technology, including crystal growth technology, sensing applications, packaging technology, and performance optimization. Despite significant progress, challenges such as heat dissipation, production costs, and yield and reliability issues need to be addressed. Future research directions may focus on improving integration with other technologies, exploring potential applications in emerging fields such as 5G communication, and addressing these challenges. Overall, GaN HEMT technology has made significant advancements and is set to play a pivotal role in various industries.

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Shu, Tianwei. "Reliability issues of GaN HEMT: Current status and challenges." Applied and Computational Engineering 23, no. 1 (November 7, 2023): 238–44. http://dx.doi.org/10.54254/2755-2721/23/20230661.

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With the development of power electronic devices, there is an increasing demand for energy-saving, emission reduction, and environmental protection. Thus, higher energy conversion efficiency of power electronic devices is required. While traditional Si-based power electronic devices have the disadvantage of low energy utilization efficiency and high thermal losses, GaN-based HEMT has significant advantages, making it a frontier and hotspot in global semiconductor research. However, the failure mechanisms that affect the reliability of GaN HEMTs are not completely comprehended. Many reliability issues affect devices performance, among which electrical reliability and thermal reliability are widely studied concerns. Electrical reliability issues contain inverse piezoelectric effect, hot electron effect, trapping effect, and mental instability. Thermal reliability issues contain self-heating effects, which are caused by the materials unsatisfying thermal conductivity, and improper structure design. This paper is focused on the current research results of the GaN HEMTs electrical reliability and thermal reliability. The first part of this paper gives a review of GaN HEMT reliability issues at their current status, and the second part outlines the challenges of GaN HEMTs in future development. This review will help researchers to better understand factors that affect GaN HEMTs reliability and help with their device design for further research.

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Sugimoto, M., H. Ueda, T. Uesugi, and T. kachi. "WIDE-BANDGAP SEMICONDUCTOR DEVICES FOR AUTOMOTIVE APPLICATIONS." International Journal of High Speed Electronics and Systems 17, no. 01 (March 2007): 3–9. http://dx.doi.org/10.1142/s012915640700414x.

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In this paper, we discuss requirements of power devices for automotive applications, especially hybrid vehicles and the development of GaN power devices at Toyota. We fabricated AlGaN/GaN HEMTs and measured their characteristics. The maximum breakdown voltage was over 600V. The drain current with a gate width of 31mm was over 8A. A thermograph image of the HEMT under high current operation shows the AlGaN/GaN HEMT operated at more than 300°C. And we confirmed the operation of a vertical GaN device. All the results of the GaN HEMTs are really promising to realize high performance and small size inverters for future automobiles.

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17

Sharbati, Samaneh, Iman Gharibshahian, Thomas Ebel, Ali A. Orouji, and Wulf-Toke Franke. "Analytical Model for Two-Dimensional Electron Gas Charge Density in Recessed-Gate GaN High-Electron-Mobility Transistors." Journal of Electronic Materials 50, no. 7 (April 20, 2021): 3923–29. http://dx.doi.org/10.1007/s11664-021-08842-7.

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AbstractA physics-based analytical model for GaN high-electron-mobility transistors (HEMTs) with non-recessed- and recessed-gate structure is presented. Based on this model, the two-dimensional electron gas density (2DEG) and thereby the on-state resistance and breakdown voltage can be controlled by varying the barrier layer thickness and Al mole fraction in non-recessed depletion-mode GaN HEMTs. The analytical model indicates that the 2DEG charge density in the channel increases from 2.4 × 1012 cm−2 to 1.8 × 1013 cm−2 when increasing the Al mole fraction from x = 0.1 to 0.4 for an experimental non-recessed-gate GaN HEMT. In the recessed-gate GaN HEMT, in addition to these parameters, the recess height can also control the 2DEG to achieve high-performance power electronic devices. The model also calculates the critical recess height for which a normally-ON GaN switch becomes normally-OFF. This model shows good agreement with reported experimental results and promises to become a useful tool for advanced design of GaN HEMTS.

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Li, Yingnan. "Comparative analysis of working principles and applications of MOSFET and HEMT." Applied and Computational Engineering 65, no. 1 (May 23, 2024): 66–74. http://dx.doi.org/10.54254/2755-2721/65/20240470.

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Semiconductor materials are currently one of the most core materials in the worlds high-tech industry, and the research and development of semiconductor materials is related to the improvement of human technological level. This paper presents a comparative study of Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) and High Electron Mobility Transistors (HEMTs), two pivotal components in electrical engineering, each with unique characteristics and functions. Despite structural similarities, MOSFETs and HEMTs differ significantly in operation and conduction methods. MOSFETs rely on an inversion layer formed at the semiconductor-oxide interface, controlled by gate voltage, for electron conduction. Conversely, HEMTs utilize a two-dimensional electron gas (2DEG) at the interface of materials like Gallium Nitride and Aluminum Gallium Nitride, offering high electron mobility crucial for performance. Both share similar I-V characteristics but differ in performance under various conditions. MOSFETs are cost-effective, ideal for mass production and general applications, while HEMTs excel in stability and performance in extreme conditions, suitable for high-performance needs. This study underscores the importance of selecting the right component based on application-specific requirements, highlighting MOSFETs for cost-efficiency and HEMTs for challenging environments. This article will provide some guidance for the research of MOSFET and HEMT.

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Wei, Yuqi, Md Maksudul Hossain, and H. Alan Mantooth. "GaN HEMT and Air Core Magnetics based Power Converters Evaluations at Cryogenic Temperature." IOP Conference Series: Materials Science and Engineering 1302, no. 1 (May 1, 2024): 012026. http://dx.doi.org/10.1088/1757-899x/1302/1/012026.

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Abstract Cryogenic power electronics is both advantageous and indispensable in many applications, like deep space probe, military electric vehicle, magnetic resonance imaging etc. Among different semiconductors, the gallium nitride (GaN) high electron mobility transistor (HEMT) is the most promising candidate for cryogenic applications with significant conduction loss and switching loss reductions. Moreover, there is no carrier freeze out effect for the GaN HEMTs, which is applicable in extreme low temperature operating conditions. In this work, the efficiency of GaN HEMTs based power converters with different power levels (from several Watts to several kiloWatts) are evaluated at cryogenic temperature. Three different commercial GaN HEMTs are used in these power converters, including the Texas Instruments LMG5200 80 V GaN half-bridge power stage with integrated gate driver, the GaN Systems 650 V bottomcooled GaN HEMT GS66516B, and the 650 V top-cooled GaN HEMT GS66516T from GaN Systems. Moreover, two different cryogenic power converter evaluation methods (cryogenic chamber and liquid nitrogen channeled through cold plate) are investigated. Three of these power converters are evaluated by using a cryogenic chamber and such that the converter operating environment temperature can be regulated. One of the power converters is evaluated by using liquid nitrogen (LN2) channeled through a cold plate, where the gate driver can be designed to operate at non-cryogenic temperatures to ensure the safe operation of the system. Due to the degraded performance of conventional magnetic components, air core magnetics are used in these power converters to improve the converter efficiency. Efficiency improvements at cryogenic temperature are observed for all the GaN HEMTs and air core magnetics based power converters, which are promising for cryogenic power electronics applications.

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Li, Xiangdong, Meng Wang, Jincheng Zhang, Rui Gao, Hongyue Wang, Weitao Yang, Jiahui Yuan, et al. "Revealing the Mechanism of the Bias Temperature Instability Effect of p-GaN Gate HEMTs by Time-Dependent Gate Breakdown Stress and Fast Sweeping Characterization." Micromachines 14, no. 5 (May 12, 2023): 1042. http://dx.doi.org/10.3390/mi14051042.

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The bias temperature instability (BTI) effect of p-GaN gate high-electron-mobility transistors (HEMTs) is a serious problem for reliability. To uncover the essential cause of this effect, in this paper, we precisely monitored the shifting process of the threshold voltage (VTH) of HEMTs under BTI stress by fast sweeping characterizations. The HEMTs without time-dependent gate breakdown (TDGB) stress featured a high VTH shift of 0.62 V. In contrast, the HEMT that underwent 424 s of TDGB stress clearly saw a limited VTH shift of 0.16 V. The mechanism is that the TDGB stress can induce a Schottky barrier lowering effect on the metal/p-GaN junction, thus boosting the hole injection from the gate metal to the p-GaN layer. This hole injection eventually improves the VTH stability by replenishing the holes lost under BTI stress. It is the first time that we experimentally proved that the BTI effect of p-GaN gate HEMTs was directly dominated by the gate Schottky barrier that impeded the hole supply to the p-GaN layer.

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Lin, Wei, Maojun Wang, Haozhe Sun, Bing Xie, Cheng P. Wen, Yilong Hao, and Bo Shen. "Suppressing Buffer-Induced Current Collapse in GaN HEMTs with a Source-Connected p-GaN (SCPG): A Simulation Study." Electronics 10, no. 8 (April 15, 2021): 942. http://dx.doi.org/10.3390/electronics10080942.

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Carbon doping in the buffer of AlGaN/GaN high-electron-mobility transistors (HEMTs) leads to the notorious current collapse phenomenon. In this paper, an HEMT structure with a source-connected p-GaN (SCPG) embedded in the carbon-doped semi-insulating buffer is proposed to suppress the buffer-induced current collapse effect. Two-dimensional transient simulation was carried out to show the successful suppression of buffer-induced current collapse in the SCPG-HEMTs compared with conventional HEMTs. The mechanism of suppressing dynamic on-resistance degradation by ejecting holes from the SCPG into the high resistive buffer layer after off-state stress is illustrated based on energy band diagrams. This paper contributes an innovative device structure to potentially solve the buffer-induced degradation of the dynamic on-resistance in GaN power devices.

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Horng, Ray-Hua, Hsiao-Yun Yeh, and Niall Tumilty. "Thermal Performance of Cu Electroplated GaN/AlGaN High-Electron-Mobility Transistors with Various-Thickness Si Substrates." Electronics 12, no. 9 (April 27, 2023): 2033. http://dx.doi.org/10.3390/electronics12092033.

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Thermal dissipation is an important issue for power devices. In this work, the impact of thermal effects on the performance of Cu electroplated GaN-based high-electron-mobility transistors (HEMTs) are considered. Electrical, thermometry and micro-Raman characterization techniques were used to correlate the effects of improved heat dissipation on device performance for GaN HEMTs with different thicknesses of Si substrate (50, 100, 150 μm), with and without an additional electroplated Cu layer. GaN HEMTs on electroplated Cu on Si (≤50 μm) demonstrate an enhanced on/off current ratio compared to bare Si substrate by a factor of ~400 (from 9.61 × 105 to 4.03 × 108). Of particular importance, surface temperature measurements reveal a much lower channel temperature for thinner HEMT devices with electroplated Cu samples compared to those without.

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Zhong, Min, Ying Xi Niu, Hai Ying Cheng, Chen Xi Yan, Zhi Yuan Liu, and Dong Bo Song. "Advances for Enhanced GaN-Based HEMT Devices with p-GaN Gate." Materials Science Forum 1014 (November 2020): 75–85. http://dx.doi.org/10.4028/www.scientific.net/msf.1014.75.

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With the development of high-voltage switches and high-speed RF circuits, the enhancement mode(E-mode) AlGaN/GaN HEMTs have become a hot topic in those fields. The E-mode GaN-based HEMTs have channel current at the positive gate voltage, greatly expanding the device in low power digital circuit applications. The main methods to realize E-mode AlGaN/GaN HEMT power devices are p-GaN gate technology, recessed gate structure, fluoride ion implantation technology and Cascode structure (Cascode). In this paper, the advantage and main realizable methods of E-mode AlGaN/GaN HEMT are briefly described. The research status and problems of E-mode AlGaN/GaN HEMT devices fabricated by p-GaN gate technology are summarized. The advances of p-GaN gate technology, and focuses on how these research results can improve the power characteristics and reliability of E-mode AlGaN/GaN HEMT by optimizing device structure and improving process technology, are discussed.

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Kuzmik, Jan, Sergey Bychikhin, Emmanuelle Pichonat, Christophe Gaquière, Erwan Morvan, Erhard Kohn, Jean-Pierre Teyssier, and Dionyz Pogany. "Self-heating phenomena in high-power III-N transistors and new thermal characterization methods developed within EU project TARGET." International Journal of Microwave and Wireless Technologies 1, no. 2 (April 2009): 153–60. http://dx.doi.org/10.1017/s1759078709990444.

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In the framework of the Top Amplifier Research Groups in a European Team (TARGET) project, we developed a new electrical method for the temperature measurement of HEMTs and performed several unique studies on the self-heating effects in AlGaN/GaN HEMTs. This method, in combination with transient interferometric mapping (TIM), provides a fundamental understanding of the heat propagation in a transient state of HEMTs. The AlGaN/GaN/Si HEMT thermal resistance was determined to be ~70 K/W after 400 ns from the start of a pulse, and the heating time constant was ~200 ns. Our experimental methods were further applied on multifinger high-power AlGaN/GaN/sapphire HEMTs. The TIM method indicates that the airbridge structure serves as a cooler, removing approximately 10% of the heat energy. In the next study we used TIM and the micro-Raman technique to quantify thermal boundary resistance (TBR) between different wafer materials and GaN epi-structure. We found TBR to be ~7 × 10−8 m2K/W for GaN/Si and ~1.2 × 10−7 m2K/W for GaN/SiC interfaces. The role of TBR at the GaN/sapphire interface was found to be less important.

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Xia, Xiaoyu, Zhiyou Guo, and Huiqing Sun. "Study of Normally-Off AlGaN/GaN HEMT with Microfield Plate for Improvement of Breakdown Voltage." Micromachines 12, no. 11 (October 27, 2021): 1318. http://dx.doi.org/10.3390/mi12111318.

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In this paper, we introduce a new type of AlGaN/GaN high electron mobility transistor (HEMT) with microfield plate (FP). We use Silvaco-ATLAS two-dimensional numerical simulation to calculate the performance of conventional HEMT and HEMT with micro-FP and analyze its principle. By studying a new charge balance method provided by HEMTs and micro-FPs, the physical mechanism of FP adjusting the HEMT potential distribution and channel electric field distribution is analyzed. The new FP structure consists of a drain field plate (D-FP), a source field plate (S-FP) and several micro-gate field plates (G-FP) to improve the output characteristics of HEMTs. By adjusting the distribution of potential and channel electric field, a wider and more uniform channel electric field can be obtained, and the breakdown voltage can be increased to 1278 V. Although the on-resistance of the HEMT is slightly increased to 5.24 Ω mm, it is still lower than other reference values. These results may open up a new and effective method for manufacturing high-power devices for power electronics applications.

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Fukuda, Koichi, Junichi Hattori, Hidehiro Asai, Mariko Ninomiya, Junya Yaita, and Junji Kotani. "Cellular automaton approach for carrier degeneracy effects on the electron mobility of high electron mobility transistors." Japanese Journal of Applied Physics 61, SC (February 17, 2022): SC1043. http://dx.doi.org/10.35848/1347-4065/ac420c.

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Abstract GaN-based high electron mobility transistors (HEMTs) are expected to have high performance in base station applications. Recently, it was reported that the combination of the Poisson–Schrödinger method and cellular automaton method is effective for predicting the mobility of channel two-dimensional electron gas of GaN HEMTs. In the operation condition of HEMT, the surface electron density of the channel is on the order of 1013 cm−2, and the effect of degeneracy cannot be ignored in calculating the mobility. Since the electron distribution function is always stably obtained by the cellular automaton method, the degeneracy effect can be considered stably. In this paper, through the comparison of different degeneracy evaluation methods, the anisotropy of the electron distribution function under the electric field acceleration is clarified to affect the HEMT mobility prediction significantly.

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Kumar, Sunil, Amit Malik, Dipendra Singh Rawal, Seema Vinayak, and Hitendra Malik. "Performance Analysis of GaN/AlGaN HEMTs Passivation using Inductively Coupled Plasma Chemical Vapour Deposition and Plasma Enhanced Chemical Vapour Deposition Techniques." Defence Science Journal 68, no. 6 (October 31, 2018): 572. http://dx.doi.org/10.14429/dsj.68.12329.

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In the present paper SiN thin film has been studied as a passivation layer and its effect on AlGaN/GaN HEMTs is investigated using two different deposition techniques i.e PECVD and ICPCVD. AlGaN/GaN HEMTs devices passivated with optimised SiN film have delivered lower gate leakage current (from μA to nA). Device source drain saturation current (Ids) increased from 400mA/mm to ~550 A/mm and the peak extrinsic trans-conductance increased from 100 mS/mm to 170 mS/mm for a 0.8 μm HEMT device. The optimised SiN passivation process has resulted in reduced current collapse and increased breakdown voltage for HEMT devices.

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Малеев, Н. А., А. П. Васильев, А. Г. Кузьменков, М. А. Бобров, М. М. Кулагина, С. И. Трошков, С. Н. Малеев, et al. "InAlAs/InGaAs/InP HEMTs с композитным каналом и улучшенными пробивными характеристиками." Письма в журнал технической физики 45, no. 21 (2019): 29. http://dx.doi.org/10.21883/pjtf.2019.21.48470.17961.

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High-electron mobility transistor (HEMT) with improved breakdown characteristics has been developed. Composite InGaAs channel structure was used in combination with fully selective double recess device fabrication process. HEMTs with T-gate length of 120 nm and width 4x30 m demonstrate maximum extrinsic transconductance of 810 mS/mm, maximum drain current density of 460 mA/mm and gate-drain reverse breakdown voltages as high as 8–10 V. Devices cut-off frequency exceed 115 GHz. Because of increased breakdown voltage and fully selective double recess fabrication process designed HEMTs are promising for medium power mm-wave MMIC amplifiers.

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Green, F. "Charge Fluctuations in High-Electron-Mobility Transistors: A Review." Australian Journal of Physics 46, no. 3 (1993): 447. http://dx.doi.org/10.1071/ph930477.

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The physics of high-electron-mobility transistors (HEMTs) plays a central role in contemporary design for millimetre-wave communications. HEMTs are the early fruits in a harvest of increasingly radical devices whose structural features are measured in nanometres. The operating principles of these devices are richly varied, and almost always far from classical. One of the tasks for device physics is to understand fluctuation phenomena, .or noise: the control of charge fluctuations is basic to high performance, yet the description of these processes remains incomplete if not obscure. This paper reviews some aspects of charge-transport noise that affect HEMT operation.

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YAMANE, YASURO, and KOICHI MURATA. "The InP-HEMT IC Technology for 40-Gbit/s Optical Communications." International Journal of High Speed Electronics and Systems 13, no. 01 (March 2003): 141–73. http://dx.doi.org/10.1142/s0129156403001569.

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We present the outline of the InP HEMT IC technology. This technology realizes InP HEMT digital ICs for 40-Gbit/s optical fiber communication systems through the integration of 0.1-μm-gate-length HEMTs, vertical diodes, capacitors, and WSiN resistors with two level interconnections. This paper describes the high-speed digital IC circuit design and fabrication in InP HEMT technology for 40-Gbit/s/channel optical communication systems. Some results on InP HEMTs' reliability are also covered. Basic circuit design techniques utilizing SCFL topology and fundamental circuit elements of the selector and D-type flip-flop are discussed in detail. The basic digital ICs of MUX, D-FF, and DEMUX ICs fabricated with 0.1-μm-gate InP HEMTs successfully operated up to 50 Gbit/s in the packaged modules. These IC modules offer large speed margins for the 43-Gbit/s OTU-3 data rate. In order to develop cost-effective optical transmitters and receivers, we designed a PLL-based CDR with a full-rate architecture. The fully monolithic integrated CDR exhibited error-free operation for 231-1 PRBS data signal at the OTU-3 bit rate of 43.0184 Gbit/s. Four-bit MUX and DEMUX ICs are other key components, and could be implemented by using InP HEMT technology. Additionally, we describe InP-IC fabrication technology with two-level inter-connection. This is already fully matured for 40-Gbit/s SSI fabrication. The uniform FET characteristics and high-yield passive component fabrication technologies support this degree of maturity. InP HEMT lifetime is 107 hours at l00°C. These results prove the InP HEMT IC fabrication technology presented here, to be highly reliable. These investigation show that robust performance and yield when realizing SSI and MSI 40-Gbit/s functions.

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Fathimulla, A., H. Hier, and J. Abrahams. "High-current, planar-doped pseudomorphic hemts Ga0.4In0.6As/Al0.48In0.52As HEMTs." Electronics Letters 24, no. 11 (May 26, 1988): 717–18. http://dx.doi.org/10.1049/el:19880485.

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Yamaoka, Yuya, Kazuhiro Ito, Akinori Ubukata, Toshiya Tabuchi, Koh Matsumoto, and Takashi Egawa. "Effect of the formation temperature of the AlN/Si interface on the vertical-direction breakdown voltages of AlGaN/GaN HEMTs on Si substrates." MRS Advances 1, no. 50 (2016): 3415–20. http://dx.doi.org/10.1557/adv.2016.431.

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ABSTRACT In this study, the initial AlN layer and the vertical-direction breakdown voltage (VDBV) of AlGaN/GaN high-electron-mobility transistors (HEMTs) were characterized. Prior to the formation of the interface between the AlN layer and the Si substrate, only trimethylaluminum (TMA) was introduced without ammonia to control the crystal quality of initial AlN layer (TMA preflow). HEMT structures were simultaneously grown on identical AlN layers on Si substrates (AlN/Si templates) grown using different TMA preflow temperatures. The density of screw- or mixed-type dislocations in the initial AlN layer decreased as the TMA preflow temperature increased. Further, the VDBV of the HEMT structure increased as the TMA preflow temperature increased. It is supposed that the screw- or mixed-type dislocations are the possible source of the vertical leakage current in the HEMT structures. The improvement in the crystal quality of the initial AlN layer affects the increase in the VDBV of the AlGaN/GaN HEMTs on Si substrates.

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Choi, Jun-Hyeok, Woo-Seok Kang, Dohyung Kim, Ji-Hun Kim, Jun-Ho Lee, Kyeong-Yong Kim, Byoung-Gue Min, Dong Min Kang, and Hyun-Seok Kim. "Enhanced Operational Characteristics Attained by Applying HfO2 as Passivation in AlGaN/GaN High-Electron-Mobility Transistors: A Simulation Study." Micromachines 14, no. 6 (May 23, 2023): 1101. http://dx.doi.org/10.3390/mi14061101.

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This study investigates the operating characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying HfO2 as the passivation layer. Before analyzing HEMTs with various passivation structures, modeling parameters were derived from the measured data of fabricated HEMT with Si3N4 passivation to ensure the reliability of the simulation. Subsequently, we proposed new structures by dividing the single Si3N4 passivation into a bilayer (first and second) and applying HfO2 to the bilayer and first passivation layer only. Ultimately, we analyzed and compared the operational characteristics of the HEMTs considering the basic Si3N4, only HfO2, and HfO2/Si3N4 (hybrid) as passivation layers. The breakdown voltage of the AlGaN/GaN HEMT having only HfO2 passivation was improved by up to 19%, compared to the basic Si3N4 passivation structure, but the frequency characteristics deteriorated. In order to compensate for the degraded RF characteristics, we modified the second Si3N4 passivation thickness of the hybrid passivation structure from 150 nm to 450 nm. We confirmed that the hybrid passivation structure with 350-nm-thick second Si3N4 passivation not only improves the breakdown voltage by 15% but also secures RF performance. Consequently, Johnson’s figure-of-merit, which is commonly used to judge RF performance, was improved by up to 5% compared to the basic Si3N4 passivation structure.

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Lee, Hanwool, Hojoon Ryu, and Wenjuan Zhu. "Thermally hardened AlGaN/GaN MIS-HEMTs based on multilayer dielectrics and silicon nitride passivation." Applied Physics Letters 122, no. 11 (March 13, 2023): 112103. http://dx.doi.org/10.1063/5.0134475.

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AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) were demonstrated to operate at temperatures of up to 600 °C. High-quality multilayer gate dielectrics (Al2O3/SiO2/SiON) were developed to enhance the thermal stability of the MIS-HEMTs at high temperatures. Furthermore, we found that silicon nitride passivation and circular structure can effectively reduce the off-state drain current, which is critical for high-temperature operations. Based on the optimized process, we demonstrated the AlGaN/GaN MIS-HEMTs with record high [Formula: see text] ratios (1011 at room temperature and 105 at 600 °C) and high transconductances (47 mS/mm at room temperature and 8 mS/mm at 600 °C for a channel length of 2.4 μm). The maximum transconductance was enhanced by ∼28% after the operation at 600 °C. Lifetime measurement of the MIS-HEMT showed stable DC characteristics with a nearly unchanged on-state drain current and threshold voltage over the course of 25-h thermal stress at 525 °C.

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Song, Wenjie, Jie Zhang, Zheyang Zheng, Sirui Feng, Xuelin Yang, Bo Shen, and Kevin J. Chen. "GaN HEMTs on low resistivity Si substrates with thick buffer layers for RF signal amplification and power conversion." AIP Advances 12, no. 4 (April 1, 2022): 045125. http://dx.doi.org/10.1063/5.0086957.

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We report GaN high-electron-mobility transistors (HEMTs) with a thick (7.7 µm) GaN buffer on a Czochralski low resistivity Si (LRS) substrate. The GaN HEMTs exhibit high performance for both radio-frequency (RF) amplification and power conversion. The thick GaN buffer was grown by means of vacancy engineering, delivering a low dislocation density of ∼1.6 × 108 cm−2, contributing to suppressed RF signal coupling to the lossy Si substrate and a high vertical voltage blocking capability. For RF performance, GaN HEMTs with a 650 nm gate exhibit an fT/ fMAX value of 25.1/32.3 GHz and a maximum output power POUT of 2.2 W/mm at 4 GHz with a drain voltage VDS of 20 V, which is comparable with the performance of RF GaN HEMTs on a high-resistivity silicon substrate without the existence of the field plate. For power performance, the vertical breakdown voltage of the wafer is 1160 V, and the three-terminal lateral breakdown voltage is 885 V in a GaN HEMT with a gate-to-drain distance of 8 µm. The thick GaN layer on the LRS substrate scheme thus provides a compelling platform for monolithic integration of high-performance RF devices and high-voltage power devices.

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Song, Wenjie, Jie Zhang, Zheyang Zheng, Sirui Feng, Xuelin Yang, Bo Shen, and Kevin J. Chen. "GaN HEMTs on low resistivity Si substrates with thick buffer layers for RF signal amplification and power conversion." AIP Advances 12, no. 4 (April 1, 2022): 045125. http://dx.doi.org/10.1063/5.0086957.

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We report GaN high-electron-mobility transistors (HEMTs) with a thick (7.7 µm) GaN buffer on a Czochralski low resistivity Si (LRS) substrate. The GaN HEMTs exhibit high performance for both radio-frequency (RF) amplification and power conversion. The thick GaN buffer was grown by means of vacancy engineering, delivering a low dislocation density of ∼1.6 × 108 cm−2, contributing to suppressed RF signal coupling to the lossy Si substrate and a high vertical voltage blocking capability. For RF performance, GaN HEMTs with a 650 nm gate exhibit an fT/ fMAX value of 25.1/32.3 GHz and a maximum output power POUT of 2.2 W/mm at 4 GHz with a drain voltage VDS of 20 V, which is comparable with the performance of RF GaN HEMTs on a high-resistivity silicon substrate without the existence of the field plate. For power performance, the vertical breakdown voltage of the wafer is 1160 V, and the three-terminal lateral breakdown voltage is 885 V in a GaN HEMT with a gate-to-drain distance of 8 µm. The thick GaN layer on the LRS substrate scheme thus provides a compelling platform for monolithic integration of high-performance RF devices and high-voltage power devices.

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Sun, Haifeng, Diego Marti, Stefano Tirelli, Andreas R. Alt, Hansruedi Benedickter, and C. R. Bolognesi. "Millimeter-wave GaN-based HEMT development at ETH-Zürich." International Journal of Microwave and Wireless Technologies 2, no. 1 (February 2010): 33–38. http://dx.doi.org/10.1017/s1759078710000164.

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We review the AlGaN/GaN high electron mobility transistor (HEMT) activities in the Millimeter-Wave Electronics Group at ETH-Zürich. Our group's main thrust in the AlGaN/GaN arena is the extension of device bandwidth to higher frequency bands. We demonstrated surprising performances for AlGaN/GaN HEMTs grown on high-resistivity (HR) silicon (111) substrates, and extended cutoff frequencies of 100 nm gate devices well into the millimeter (mm)-wave domain. Our results narrow the performance gap between GaN-on-SiC (or sapphire) and GaN-on-silicon and establish GaN-on-Si as a viable technology for low-cost mm-wave electronics. We here contrast the difference in behaviors observed in our laboratory between nominally identical devices built on high-resistivity silicon (HR-Si) and on sapphire substrates; we show high-speed devices with high-cutoff frequencies and breakdown voltages which combine fT,MAX × BV products as high as 5–10 THz V, and show AlGaN/GaN HEMTs with fT values exceeding 100 GHz on HR-Si. Although the bulk of our activities have so far focused on AlGaN/GaN HEMTs on HR-Si, our process produces excellent device performances when applied to GaN HEMTs on SiC as well: 100 nm gate transistors with fT > 125 GHz have been realized at ETH-Zürich.

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Driss Bouguenna, Abbès Beloufa, Khaled Hebali, and Sajad Ahmad Loan. "Investigation of the Electrical Characteristics of AlGaN/AlN/GaN Heterostructure MOS-HEMTs with TiO2 High-k Gate Insulator." International Journal of Nanoelectronics and Materials (IJNeaM) 16, no. 3 (October 22, 2024): 607–20. http://dx.doi.org/10.58915/ijneam.v16i3.1325.

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This paper investigates the impact of TiO2 high-k gate insulator on the electrical characteristics of AlGaN/AlN/GaN MOS-HEMT transistors using MATLAB and Atlas-TCAD simulation software. The physical analytical model of the MOS-HEMTs is used for simulation from Al2O3, HfO2, and TiO2 as the gate dielectric materials, which provide higher performance and reliability of the MOS-HEMT devices. The device shows a good improvement in its result of the DC and AC characteristics with different permittivity of insulator materials. Thus, the DC and AC performance of GaN MOS-HEMTs is higher than with other insulators, such as Al2O3 and HfO2 by using TiO2 as the gate dielectric. Moreover, the simulation results proved that TiO2 is the better gate dielectric material to enhance the electrical reliability of the power switching devices for high-temperature applications such as electric automobiles.

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Han, Lili, Xiansheng Tang, Zhaowei Wang, Weihua Gong, Ruizhan Zhai, Zhongqing Jia, and Wei Zhang. "Research Progress and Development Prospects of Enhanced GaN HEMTs." Crystals 13, no. 6 (June 4, 2023): 911. http://dx.doi.org/10.3390/cryst13060911.

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With the development of energy efficiency technologies such as 5G communication and electric vehicles, Si-based GaN microelectronics has entered a stage of rapid industrialization. As a new generation of microwave and millimeter wave devices, High Electron Mobility Transistors (HEMTs) show great advantages in frequency, gain, and noise performance. With the continuous advancement of material growth technology, the epitaxial growth of semiconductor heterojunction can accurately control doping level, material thickness, and alloy composition. Consequently, HEMTs have been greatly improved from material structure to device structure. Device performance has also been significantly improved. In this paper, we briefly describe MOCVD growth technology and research progress of GaN HEMT epitaxial films, examine and compare the “state of the art” of enhanced HEMT devices, analyze the reliability and CMOS compatibility of GaN devices, and look to the future directions of possible development.

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Bottaro, Enrico Alfredo, and Santi Agatino Rizzo. "An Overview of Strengths and Weaknesses in Using MOSFET Experience for Modeling GaN HEMT." Energies 16, no. 18 (September 12, 2023): 6574. http://dx.doi.org/10.3390/en16186574.

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GaN high electron mobility transistors (HEMTs) represent an emerging and key enabling technology for obtaining highly efficient and compact power electronic systems. The use of circuit models of power devices is essential for the optimal design of power converters, but while they have been deeply investigated for power MOSFETs and IGBTs, GaN HEMT models are still in their early stages. This paper first discusses the main similarities and differences between conventional MOSFETs and GaN HEMTs in terms of the datasheet information that the device manufacturers use to obtain the behavioral models that they usually provide as Spice-like netlists. Then, it highlights the strengths and weaknesses of using the behavioral models of MOSFET for GaN HEMT. To achieve this aim, a study of the existing GaN HEMT models revealed the lack of a proper modeling strategy for the dynamic conduction resistance, which is the most critical aspect of HEMT modeling. The difficulty is due to the dependence of the dynamic conduction resistance on quantities related to the application, which is a behavior absent in power MOSFETs. Consequently, future research efforts on GaN HEMT modeling must face this issue.

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Lee, Jun-Ho, Jun-Hyeok Choi, Woo-Seok Kang, Dohyung Kim, Byoung-Gue Min, Dong Min Kang, Jung Han Choi, and Hyun-Seok Kim. "Analysis of Operational Characteristics of AlGaN/GaN High-Electron-Mobility Transistor with Various Slant-Gate-Based Structures: A Simulation Study." Micromachines 13, no. 11 (November 11, 2022): 1957. http://dx.doi.org/10.3390/mi13111957.

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This study investigates the operational characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying a slant-gate structure and drain-side extended field-plate (FP) for improved breakdown voltage. Prior to the analysis of slant-gate-based HEMT, simulation parameters were extracted from the measured data of fabricated basic T-gate HEMTs to secure the reliability of the results. We suggest three different types of slant-gate structures that connect the basic T-gate electrode boundary to the 1st and 2nd SiN passivation layers obliquely. To consider both the breakdown voltage and frequency characteristics, the DC and RF characteristics of various slant-gate structures including the self-heating effect were analyzed by TCAD simulation. We then applied a drain-side extended FP to further increase the breakdown voltage. The maximum breakdown voltage was achieved at the FP length of 0.4 μm. Finally, we conclude that the slant-gate structures can improve breakdown voltage by up to 66% without compromising the frequency characteristics of the HEMT. When the drain-side FP is applied to a slant-gate structure, the breakdown voltage is further improved by up to 108%, but the frequency characteristics deteriorate. Therefore, AlGaN/GaN HEMTs with an optimized slant-gate-based structure can ultimately be a promising candidate for high-power and high-frequency applications.

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Wang, Zhiheng, Yanrong Cao, Xinxiang Zhang, Chuan Chen, Linshan Wu, Maodan Ma, Hanghang Lv, et al. "Simulation of Single-Event Transient Effect for GaN High-Electron-Mobility Transistor." Micromachines 14, no. 10 (October 19, 2023): 1948. http://dx.doi.org/10.3390/mi14101948.

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A GaN high-electron-mobility transistor (HEMT) was simulated using the semiconductor simulation software Silvaco TCAD in this paper. By constructing a two-dimensional structure of GaN HEMT, combined with key models such as carrier mobility, the effects of a different state, different incidence position, different drain voltage, different LET values, and a different incidence angle on the single-event transient effect of GaN HEMT are simulated. LET stands for the linear energy transfer capacity of a particle, which refers to the amount of energy transferred by the particle to the irradiated substance on the unit path. The simulation results show that for GaN HEMTs, the single-event transient effect is more obvious when the device is in off-state than in on-state. The most sensitive location of GaN HEMTs to the single-event effect is in the region near the drain. The peak transient current increases with the increase in the drain bias and incident ion LET values. The drain charge collection time increases with the angle of incidence of heavy ion.

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Grandpierron, François, Elodie Carneiro, Lyes Ben-Hammou, Jeong-Sun Moon, and Farid Medjdoub. "Understanding and Quantifying the Benefit of Graded Aluminum Gallium Nitride Channel High-Electron Mobility Transistors." Micromachines 15, no. 11 (November 8, 2024): 1356. http://dx.doi.org/10.3390/mi15111356.

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Graded AlGaN channel High-Electron Mobility Transistor (HEMT) technology is emerging as a strong candidate for millimeter-wave applications, as superior efficiency and linearity performances can be achieved. In this paper, graded channel AlGaN/GaN HEMTs are investigated with the aim of further understanding the benefit of the graded AlGaN channel compared to more conventional GaN channel HEMTs. Our study employed a comprehensive simulation workflow including an extensive calibration of direct current (DC), S-parameter, large signal, and linearity characteristics at 30 GHz. Through device modeling and implementation of circuit-level simulation using Advanced Design System (ADS, 2023) software, both linearity and large signal performances could be mimicked remarkably. In agreement with previous studies, the results show that graded channel technology allows for a modified electron confinement leading to a 3D electron gas (3DEG). Consequently, the electric field peak inside of the channel is reduced without degrading the radio frequency (RF) performance, as the electron velocity is improved, thus offering a more linear transconductance and better linearity performances. As a result, for graded AlGaN channel HEMTs, a 6 dB output power back-off from peak power-added efficiency (PAE) is needed to achieve a carrier with a third-order intermodulation (C/IM3) ratio of 30 dBc against 9 dB for conventional AlGaN/GaN HEMTs with a lower associated PAE.

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Jadli, Utkarsh, Faisal Mohd-Yasin, Hamid Amini Moghadam, Peyush Pande, Mayank Chaturvedi, and Sima Dimitrijev. "Modeling Power GaN-HEMTs Using Standard MOSFET Equations and Parameters in SPICE." Electronics 10, no. 2 (January 9, 2021): 130. http://dx.doi.org/10.3390/electronics10020130.

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The device library in the standard circuit simulator (SPICE) lacks a gallium nitride based high-electron-mobility-transistor (GaN-HEMT) model, required for the design and verification of power-electronic circuits. This paper shows that GaN-HEMTs can be modeled by selected equations from the standard MOSFET LEVEL 3 model in SPICE. A method is proposed for the extraction of SPICE parameters in these equations. The selected equations and the proposed parameter-extraction method are verified with measured static and dynamic characteristics of commercial GaN-HEMTs. Furthermore, a double pulse test is performed in LTSpice and compared to its manufacturer model to demonstrate the effectiveness of the MOSFET LEVEL 3 model. The advantage of the proposed approach to use the MOSFET LEVEL 3 model, in comparison to the alternative behavioral-based model provided by some manufacturers, is that users can apply the proposed method to adjust the parameters of the MOSFET LEVEL 3 model for the case of manufacturers who do not provide SPICE models for their HEMTs.

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Jadli, Utkarsh, Faisal Mohd-Yasin, Hamid Amini Moghadam, Peyush Pande, Mayank Chaturvedi, and Sima Dimitrijev. "Modeling Power GaN-HEMTs Using Standard MOSFET Equations and Parameters in SPICE." Electronics 10, no. 2 (January 9, 2021): 130. http://dx.doi.org/10.3390/electronics10020130.

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The device library in the standard circuit simulator (SPICE) lacks a gallium nitride based high-electron-mobility-transistor (GaN-HEMT) model, required for the design and verification of power-electronic circuits. This paper shows that GaN-HEMTs can be modeled by selected equations from the standard MOSFET LEVEL 3 model in SPICE. A method is proposed for the extraction of SPICE parameters in these equations. The selected equations and the proposed parameter-extraction method are verified with measured static and dynamic characteristics of commercial GaN-HEMTs. Furthermore, a double pulse test is performed in LTSpice and compared to its manufacturer model to demonstrate the effectiveness of the MOSFET LEVEL 3 model. The advantage of the proposed approach to use the MOSFET LEVEL 3 model, in comparison to the alternative behavioral-based model provided by some manufacturers, is that users can apply the proposed method to adjust the parameters of the MOSFET LEVEL 3 model for the case of manufacturers who do not provide SPICE models for their HEMTs.

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46

Lin, Chao-Wei, and Hsien-Chin Chiu. "GaN-Based High-kPraseodymium Oxide Gate MISFETs withP2S5/(NH4)2SX+ UV Interface Treatment Technology." Active and Passive Electronic Components 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/459043.

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This study examines the praseodymium-oxide- (Pr2O3-) passivated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with high dielectric constant in which the AlGaN Schottky layers are treated with P2S5/(NH4)2SX+ ultraviolet (UV) illumination. An electron-beam evaporated Pr2O3insulator is used instead of traditional plasma-assisted chemical vapor deposition (PECVD), in order to prevent plasma-induced damage to the AlGaN. In this work, the HEMTs are pretreated with P2S5/(NH4)2SXsolution and UV illumination before the gate insulator (Pr2O3) is deposited. Since stable sulfur that is bound to the Ga species can be obtained easily and surface oxygen atoms are reduced by the P2S5/(NH4)2SXpretreatment, the lowest leakage current is observed in MIS-HEMT. Additionally, a low flicker noise and a low surface roughness (0.38 nm) are also obtained using this novel process, which demonstrates its ability to reduce the surface states. Low gate leakage current Pr2O3and high-kAlGaN/GaN MIS-HEMTs, with P2S5/(NH4)2SX+ UV illumination treatment, are suited to low-noise applications, because of the electron-beam-evaporated insulator and the new chemical pretreatment.

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Hong, Sejun, Abu ul Hassan Sarwar Rana, Jun-Woo Heo, and Hyun-Seok Kim. "DC Characteristics of AlGaN/GaN HEMTs Using a Dual-Gate Structure." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7467–71. http://dx.doi.org/10.1166/jnn.2015.11135.

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Multiple techniques such as fluoride-based plasma treatment, a p-GaN or p-AlGaN gate contact, and a recessed gate structure have been employed to modulate the threshold voltage of AlGaN/GaN-based high-electron-mobility transistors (HEMTs). In this study, we present dual-gate AlGaN/GaN HEMTs grown on a Si substrate, which effectively shift the threshold voltage in the positive direction. Experimental data show that the threshold voltage is shifted from −4.2 V in a conventional single-gate HEMT to −2.8 V in dual-gate HEMTs. It is evident that a second gate helps improve the threshold voltage by reducing the two-dimensional electron gas density in the channel. Furthermore, the maximum drain current, maximum transconductance, and breakdown voltage values of a single-gate device are not significantly different from those of a dual-gate device. For the fabricated single- and dual-gate devices, the values of the maximum drain current are 430 mA/mm and 428 mA/mm, respectively, whereas the values of the maximum transconductance are 83 mS/mm and 75 mS/mm, respectively.

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Wu, Chih-Chiang, Ching-Yao Liu, Sandeep Anand, Wei-Hua Chieng, Edward-Yi Chang, and Arnab Sarkar. "Comparisons on Different Innovative Cascode GaN HEMT E-Mode Power Modules and Their Efficiencies on the Flyback Converter." Energies 14, no. 18 (September 20, 2021): 5966. http://dx.doi.org/10.3390/en14185966.

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The conventional cascode structure for driving depletion-mode (D-mode) gallium nitride (GaN) high electron mobility transistors (HEMTs) raises reliability concerns. This is because of the possibility of the gate to source voltage of the GaN HEMT surging to a negative voltage during the turn off transition. The existing solutions for this problem in the literature produce additional drawbacks such as reducing the switching frequency or introducing many additional components. These drawbacks may outweigh the advantages of using a GaN HEMT over its silicon (Si) alternative. This paper proposes two innovative gate drive circuits for D-mode GaN HEMTs—namely the GaN-switching based cascode GaN HEMT and the modified GaN-switching based cascode GaN HEMT. In these schemes, the Si MOSFET in series with the D-mode GaN HEMT is always turned on during regular operation. The GaN HEMT is then switched on and off by using a charge pump based circuit and a conventional gate driver. Since the GaN HEMT is driven independently, the highly negative gate-to-source voltage surge during turn off is avoided, and in addition, high switching frequency operation is made possible. Only two diodes and one capacitor are used in each of the schemes. The application of the proposed circuits is experimentally demonstrated in a high voltage flyback converter, where more than 96% efficiency is obtained for 60 W output load.

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Sreenivasa Rao, Devireddy, Malluri Sirisha, Deepthi Tumkur Srinivas Murthy, Nayana Dunthur Krishne Gowda, Bukya Balaji, and Padakanti Kiran Kumar. "Design and optimization of high electron mobility transistor with high-k dielectric material integration." International Journal of Electrical and Computer Engineering (IJECE) 14, no. 4 (August 1, 2024): 3855. http://dx.doi.org/10.11591/ijece.v14i4.pp3855-3862.

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We have developed and simulated a high electron mobility transistor (HEMT) operating in the 5 nm regime. This HEMT uses hafnium oxide (HfO2), a high-k dielectric material, to create an undoped region (UR) beneath the gate. While the gate and undoped regions share equal thickness, the channel length differs. This innovative undoped under the gate dielectric HEMT design mitigates the maximum electric field (V) within the channel area, leading to a significant increase in drain current. The utilization of a high-k dielectric in the HEMT structure results in a saturated Ion current that is 60% higher compared to conventional structures. Specifically, we use an AlGaN/GaN/SiC-based HEMT with an intrinsic section below the gate, using HfO2 as the high-k dielectric substantial, for applications requiring high power and high-frequency power amplifiers. Compare this advanced HEMT design to conventional HEMTs and you will see improved conductivity, a greater drain current (Id), a 54% increase in transconductance (Gm), and a lower on-resistance (Ron). Additionally, advancements in the electric field in the Y direction are seen. This HEMT structure exhibits superior performance compared to alternative materials analyzed. The integration of AlGaN/GaN materials in HEMTs opens up extensive opportunities in the realms of radio frequency very large-scale integration (VLSI) and power electronics.

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Yu, Qian, Chunzhou Shi, Ling Yang, Hao Lu, Meng Zhang, Xu Zou, Mei Wu, et al. "Improved DC and RF Characteristics of GaN-Based Double-Channel HEMTs by Ultra-Thin AlN Back Barrier Layer." Micromachines 15, no. 10 (September 30, 2024): 1220. http://dx.doi.org/10.3390/mi15101220.

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In order to improve the off-state and breakdown characteristics of double-channel GaN HEMTs, an ultra-thin barrier layer was chosen as the second barrier layer. The strongly polarized and ultra-thin AlN sub-barrier and the InAlN sub-barrier are great candidates. In this article, the two epitaxial structures, AlGaN/GaN/AlN/GaN (sub-AlN) HEMTs and AlGaN/GaN/InAlN/GaN (sub-InAlN) HEMTs, were compared to select a more suitable sub-barrier layer. Through TEM images of the InAlN barrier layer, the segregation of In components can be seen, which decreases the mobility of the second channel. Thus, the sub-AlN HEMTs have a higher output current density and transconductance than those of the sub-InAlN HEMTs. Because the high-quality AlN barrier layer shields the gate leakage current, a 294 V breakdown voltage was achieved by the sub-AlN HEMTs, which is higher than the 121 V of the sub-InAlN HEMTs. The current gain cut-off frequency (fT) and maximum oscillation frequency (fmax) of the sub-AlN HEMTs are higher than that of the sub-InAlN HEMTs from low to high bias voltage. The power-added efficiency (PAE) and output power density (Pout) of the sub-AlN HEMTs are 57% and 11.3 W/mm at 3.6 GHz and 50 V of drain voltage (Vd), respectively. For the sub-InAlN HEMTs, the PAE and Pout are 41.4% and 8.69 W/mm, because of the worse drain lag ratio. Thus, the Pout of the sub-AlN HEMTs is higher than that of the sub-InAlN HEMTs.

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Journal articles on the topic 'HEMTs'

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