Journal articles: 'Buffer layer architecture'

1

Oh, Yong Jun, Jung Seok Ra, and Ui Gil Lee. "Effects of Deposition Parameters on the Crystallinities of CeO₂ and Y₂O₃ Buffer Layers on Textured Ni Deposited by Magnetron Sputtering." Solid State Phenomena 124-126 (June 2007): 779–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.779.

Full text

Abstract:

The epitaxial growth conditions of CeO2 and Y2O3 single buffer layers on textured Ni tapes were examined using rf magnetron sputtering, and the process conditions for the sequential and mixture buffer layers of these two materials were investigated respectively in order to develop a more simplified buffer architecture. The CeO2 single layer exhibited a well developed (200) epitaxial growth at Ar/10%O2 gas below 450°C, although the epitaxial property was decreased with increasing layer thickness. With regard to the deposition of Y2O3 on Ni, the epitaxial growth was not successful. The epitaxy of Y2O3 on Ni was very sensitive to the O2 gas pressure during sputtering. The repeated sequential architecture of the CeO2 and Y2O3 layers exhibited a good epitaxial property at 400°C/(Ar/10%O2) for the initial CeO2 layer and 700°C/Ar and 700°C/(Ar/10%O2) for the subsequent Y2O3 and CeO2 layers, respectively. The Y-doped CeO2 buffers with (200) epitaxy were successfully obtained by the co-sputtering of Ce and Y metals in a reactive gas condition, and the maximum target Y/Ce ratio for the epitaxy was about 1/10.

APA, Harvard, Vancouver, ISO, and other styles

2

Gianni, L., A. Baldini, M. Bindi, A. Gauzzi, S. Rampino, and S. Zannella. "High Jc coated conductors with a simple buffer layer architecture." Physica C: Superconductivity and its Applications 426-431 (October 2005): 872–77. http://dx.doi.org/10.1016/j.physc.2005.03.037.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Cheng, Wei-Kai, Xiang-Yi Liu, Hsin-Tzu Wu, Hsin-Yi Pai, and Po-Yao Chung. "Reconfigurable Architecture and Dataflow for Memory Traffic Minimization of CNNs Computation." Micromachines 12, no. 11 (November 5, 2021): 1365. http://dx.doi.org/10.3390/mi12111365.

Full text

Abstract:

Computation of convolutional neural network (CNN) requires a significant amount of memory access, which leads to lots of energy consumption. As the increase of neural network scale, this phenomenon is further obvious, the energy consumption of memory access and data migration between on-chip buffer and off-chip DRAM is even much more than the computation energy on processing element array (PE array). In order to reduce the energy consumption of memory access, a better dataflow to maximize data reuse and minimize data migration between on-chip buffer and external DRAM is important. Especially, the dimension of input feature map (ifmap) and filter weight are much different for each layer of the neural network. Hardware resources may not be effectively utilized if the array architecture and dataflow cannot be reconfigured layer by layer according to their ifmap dimension and filter dimension, and result in a large quantity of data migration on certain layers. However, a thorough exploration of all possible configurations is time consuming and meaningless. In this paper, we propose a quick and efficient methodology to adapt the configuration of PE array architecture, buffer assignment, dataflow and reuse methodology layer by layer with the given CNN architecture and hardware resource. In addition, we make an exploration on the different combinations of configuration issues to investigate their effectiveness and can be used as a guide to speed up the thorough exploration process.

APA, Harvard, Vancouver, ISO, and other styles

4

Stan, L., P. N. Arendt, I. O. Usov, H. Wang, S. R. Foltyn, B. Maiorov, J. R. Groves, R. F. DePaula, and Y. Li. "Engineered reactive cosputtered SmxZr1–xOythin films as buffer layers for YBa2Cu3O7−δcoated conductors." Journal of Materials Research 22, no. 4 (April 2007): 1082–86. http://dx.doi.org/10.1557/jmr.2007.0138.

Full text

Abstract:

This study shows that biaxially textured SmxZr1−xOy(SZO) with a wide range of compositions (0.06 <x< 0.75) can be grown directly on ion-beam-assisted deposition (IBAD) MgO template using reactive cosputtering. The SZO crystal structure can be changed, and the lattice parameter can be tailored (from 5.23 to 5.49 Å) by changing the composition. We have developed a simplified high-temperature superconducting coated conductor using SZO as the buffer layer. YBa2Cu3O7−δ(YBCO) films grown by pulsed laser deposition on the SZO buffered IBAD MgO have self-field critical current densities (Jc) in the 2–4 MA/cm2range. The in-field measurements demonstrate that high-quality YBCO films can be grown on SZO buffered IBAD MgO. The present results are especially important because they were obtained on coated conductors with the simpler architecture by eliminating the additional homoepitaxial layer of MgO. This translates in faster production and lower manufacturing cost.

APA, Harvard, Vancouver, ISO, and other styles

5

ARBER, LEON, and SCOTT PAKIN. "THE IMPACT OF MESSAGE-BUFFER ALIGNMENT ON COMMUNICATION PERFORMANCE." Parallel Processing Letters 15, no. 01n02 (March 2005): 49–65. http://dx.doi.org/10.1142/s0129626405002052.

Full text

Abstract:

Of the many factors that contribute to communication performance, perhaps one of the least investigated is that of message-buffer alignment. Although the generally accepted practice is to page-align buffer memory for best performance, our studies show that the actual relationship of buffer alignment to communication performance cannot be expressed with such a simple formula. This paper presents a case study in which porting a simple network performance test from one language to another resulted in a large performance discrepancy even though both versions of the code consist primarily of calls to messaging-layer functions. Careful analysis of the two code versions revealed that the discrepancy relates to the alignment in memory of the message buffers. Further investigation revealed some surprising results about the impact of message-buffer alignment on communication performance: (1) different networks and node architectures prefer different buffer alignments; (2) page-aligned memory does not always give the best possible performance, and, in some cases, actually yields the worst possible performance; and, (3) on some systems, the most significant factor affecting network performance is the relative alignment of send and receive buffers with respect to each other.

APA, Harvard, Vancouver, ISO, and other styles

6

MUKHERJEE, SANKHA S., and SYED S. ISLAM. "EFFECTS OF BUFFER LAYER THICKNESS AND DOPING CONCENTRATION ON SiC MESFET CHARACTERISTICS." International Journal of High Speed Electronics and Systems 14, no. 03 (September 2004): 890–96. http://dx.doi.org/10.1142/s0129156404003009.

Full text

Abstract:

Two-dimensional simulations have been carried out using the Atlas® device simulator to investigate the effects of the buffer layer thickness and doping concentration on the electrical characteristics of the SiC MESFET. The variations of transconductance, output resistance, gate-source capacitance, gate-drain capacitance and (cutoff frequency) f T with respect to the change in buffer layer thickness and doping concentration have been investigated. It is observed that the performances of MESFET can be improved by reducing the leakage of channel carrier into the substrate at high drain bias, which is achieved by increasing buffer layer doping density and/or increasing buffer layer thickness. For a SiC MESFET with buffer layer thickness of 0.3μm and gate length of 1μm, drain current increases from 0.1A/ μm to above 0.45A/ μm as the buffer layer doping density is decreased from 1.9 × 1017 cm -3 to 1 × 1016 cm -3. The simulations were carried out at a gate-source voltage of –1V and a drain-source voltage of 15V. Under similar conditions, the output resistance decreases from 1.2 × 106 Ω/μ m to 1.2 × 106 Ω/μ m , and the transconductance decreases from 5.9mS/ μm to 5.3mS/ μm, and f T decreases from 11GHz to 8GHz.

APA, Harvard, Vancouver, ISO, and other styles

7

Raphael, Johanna, Tedi Kujofsa, and J. E. Ayers. "Comparison of Buffer Layer Grading Approaches in InGaAs/GaAs (001)." International Journal of High Speed Electronics and Systems 29, no. 01n04 (March 2020): 2040002. http://dx.doi.org/10.1142/s0129156420400029.

Full text

Abstract:

Metamorphic semiconductor devices often utilize compositionally-graded buffer layers for the accommodation of the lattice mismatch with controlled threading dislocation density and residual strain. Linear or step-graded buffers have been used extensively in these applications, but there are indications that sublinear, superlinear, S-graded, or overshoot graded structures could offer advantages in the control of defect densities. In this work we compare linear, step-graded, and nonlinear grading approaches in terms of the resulting strain and dislocations density profiles using a state-of-the-art model for strain relaxation and dislocation dynamics. We find that sublinear grading results in lower surface dislocation densities than either linear or superlinear grading approaches.

APA, Harvard, Vancouver, ISO, and other styles

8

Aytug, T., J. Z. Wu, B. W. Kang, D. T. Verebelyi, C. Cantoni, E. D. Specht, A. Goyal, M. Paranthaman, and D. K. Christen. "An all-sputtered buffer layer architecture for high-Jc YBa2Cu3O7−δ coated conductors." Physica C: Superconductivity 340, no. 1 (November 2000): 33–40. http://dx.doi.org/10.1016/s0921-4534(00)01331-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Wang, H., S. R. Foltyn, P. N. Arendt, Q. X. Jia, J. L. MacManus-Driscoll, L. Stan, Y. Li, X. Zhang, and P. C. Dowden. "Microstructure of SrTiO3 buffer layers and itseffects on superconducting properties ofYBa2Cu3O7-δ coated conductors." Journal of Materials Research 19, no. 6 (June 2004): 1869–75. http://dx.doi.org/10.1557/jmr.2004.0244.

Full text

Abstract:

A thin layer of SrTiO3 (STO) has successfully been used as a buffer layer to grow high-quality superconducting YBa2Cu3O7-δ(YBCO) thick films on polycrystalline metal substrates with a biaxially oriented MgO template produced by ion-beam-assisted deposition. Using this architecture, 1.5-μm-thick YBCO films with an in-plane mosaic spread in the range of 2.5° to 3.5° in full width at half-maximum and critical current density over 2 × 10 6A/cm2 in self-field at 75 K have routinely been achieved. It is interesting to note that the pulsed laser deposition growth conditions of SrTiO3 buffer layers, such as growth temperature and oxygen pressure, have strong effects on the superconducting properties of YBCO. Detailed studies using transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were used to explore the microstructures of STO deposited at different conditions and to understand further their effects on the growth and properties of YBCO films.

APA, Harvard, Vancouver, ISO, and other styles

10

RAJAN, SIDDHARTH, ARPAN CHAKRABORTY, UMESH K. MISHRA, CHRISTIANE POBLENZ, PATRICK WALTEREIT, and JAMES S. SPECK. "MBE-Grown AlGaN/GaN HEMTs on SiC." International Journal of High Speed Electronics and Systems 14, no. 03 (September 2004): 732–37. http://dx.doi.org/10.1142/s0129156404002752.

Full text

Abstract:

We report on the development of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on SiC using plasma-assisted molecular beam epitaxy (MBE). In this work, we show that performance comparable to state-of-the-art AlGaN/GaN HEMTs can be achieved using MBE-grown material. Buffer leakage was an important limiting factor for these devices. The use of either carbon-doped buffers, or low Al/N ratio in the nucleation layer growth were effective in reducing buffer leakage. Studies varying the thickness and concentration of the carbon doping were carried out to determine the effect of different carbon doping profiles on the insulating and dispersive properties of buffers, On devices without field plates, at 4 GHz an output power density of 12 W/mm was obtained with a power-added efficiency (PAE) of 46 % and gain of 14 dB. 15.6 W/mm with PAE of 56 % was obtained from these devices after field-plating. Two-tone linearity measurements of these devices were also carried out. At a C/I 3 level of 30 dBc, the devices measured had an output power of 1.9 W/mm with a PAE of 53 %. The effect of the Al/N ratio in the AlN nucleation layer on buffer leakage was studied. N -rich conditions yielded highly insulating GaN buffers without carbon doping. At 4 GHz, devices without field plates delivered 4.8 W/mm with a PAE of 62 %. At a higher drain bias (50 V), 8.1 W/mm with a PAE of 38 % was achieved.

APA, Harvard, Vancouver, ISO, and other styles

11

Sathyamurthy, S., M. Paranthaman, H. Y. Zhai, S. Kang, T. Aytug, C. Cantoni, K. J. Leonard, et al. "Chemical solution deposition of lanthanum zirconate barrier layers applied to low-cost coated-conductor fabrication." Journal of Materials Research 19, no. 7 (July 2004): 2117–23. http://dx.doi.org/10.1557/jmr.2004.0281.

Full text

Abstract:

Epitaxial lanthanum zirconate (LZO) buffer layers have been grown by sol-gel processing on Ni–W substrates. We report on the application of these oxide films as seed and barrier layers in coated conductor fabrication as potentially simpler, lower cost coated-conductor architecture. The LZO films, about 80–100-nm thick, were found to have dense, crack-free surfaces with high surface crystallinity. Using 0.2-μm YBCO deposited by pulsed laser deposition, a critical current density of 2 MA/cm2 has been demonstrated on the LZO films (YBCO/LZO/Ni–W). Using 0.8-μm YBCO deposited using metal organic decomposition, a critical current density of 1.7 MA/cm2 and a critical current of 135 A/cm have been demonstrated on the LZO barrier layer with a sputtered CeO2 cap layer (YBCO/CeO2/LZO/Ni–W). These results offer promise to replace several of the vacuum-deposited layers in the typical coated conductor architecture (YBCO/CeO2/YSZ/Y2O3/Ni/Ni-W).

APA, Harvard, Vancouver, ISO, and other styles

12

Lv, Zhaoyue, Zhenbo Deng, Denghui Xu, Xiufang Li, and Yong Jia. "Efficient organic light-emitting diodes with C60 buffer layer." Displays 30, no. 1 (January 2009): 23–26. http://dx.doi.org/10.1016/j.displa.2008.10.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Lee, Sang-Won, Dong-Joo Park, Tae-Sun Chung, Dong-Ho Lee, Sangwon Park, and Ha-Joo Song. "A log buffer-based flash translation layer using fully-associative sector translation." ACM Transactions on Embedded Computing Systems 6, no. 3 (July 2007): 18. http://dx.doi.org/10.1145/1275986.1275990.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Kim, Hye In, Jung Min Sung, Hyung Uk Cho, Yong Jo Kim, Young Gwan Park, and Woo Young Choi. "LTPS TFTs with an Amorphous Silicon Buffer Layer and Source/Drain Extension." Electronics 10, no. 1 (December 28, 2020): 29. http://dx.doi.org/10.3390/electronics10010029.

Full text

Abstract:

A low leakage poly-Si thin film transistor (TFT) is proposed featuring hydrogenated amorphous silicon (a-Si:H) buffer layer and source/drain extension (SDE) by using technology computer aided design (TCAD) simulation. This architecture reduces off-current effectively by suppressing two leakage current generation mechanisms with little on-current loss. The amorphous silicon buffer layer having large bandgap energy (Eg) suppresses both thermal generation and minimum leakage current, which leads to higher on/off current ratio. In addition, the formation of lightly doped region near the drain alleviates the field-enhanced generation in the off-state by reducing electric field. TCAD simulation results show that the proposed TFT shows more than three orders of magnitude lower off-current than low-temperature polycrystalline silicon (LTPS) TFTs, while maintaining on-current.

APA, Harvard, Vancouver, ISO, and other styles

15

EINFELDT, S., Z. J. REITMEIER, and R. F. DAVIS. "STRAIN OF GaN LAYERS GROWN USING 6H-SiC(0001) SUBSTRATES WITH DIFFERENT BUFFER LAYERS." International Journal of High Speed Electronics and Systems 14, no. 01 (March 2004): 39–50. http://dx.doi.org/10.1142/s0129156404002223.

Full text

Abstract:

Gallium nitride films of increasing thickness have been grown on either AlN or AlGaN substrates. The state of stress of these biaxially stressed layers gradually changed from compression to tension with regard to both their average strain and their local strain along the [0001] growth direction. The components of both the compressive and tensile stresses are caused by the mismatch in lattice parameters between the GaN and the buffer layer and the mismatch in the coefficients of thermal expansion between GaN and SiC , respectively. The compressive stress is partially relieved within the first 20 nm in the GaN film grown on the AlN buffer layer. The relief of the remaining stress follows an exponential dependence on the thickness of the GaN layer with values for the characteristic decay length of 0.24 μm and 0.64 μm for the AlN and AlGaN buffer layer, respectively. The relaxation mechanism is discussed in terms of the formation of misfit dislocations via surface undulations.

APA, Harvard, Vancouver, ISO, and other styles

16

Jafarov, Maarif Ali, E. F. Nasirov, and S. A. Jahangirova. "ZnS/Cu2ZnSnS4/CdTe/In Thin Film Structure for Solar Cells." JOURNAL OF ADVANCES IN PHYSICS 14, no. 2 (June 5, 2018): 5435–41. http://dx.doi.org/10.24297/jap.v14i2.7395.

Full text

Abstract:

A solar cell with glass/ITO/ZnS/Cu2ZnSnS4/CdTe/In structure has been fabricated using all-electrodeposited ZnS, Cu2ZnSnS4 and CdTe thin films. The three semiconductor layers were electrodeposited using a two-electrode system for process simplification. The incorporation of a wide bandgap amorphous ZnS as a buffer/window layer to form ITO/ZnS/Cu2ZnSnS4/CdTe/In solar cell resulted in the formation of this 3-layer device structure. This has yielded corresponding improvement in all the solar cell parameters resulting in a conversion efficiency >12% under AM1.5 illumination conditions at room temperature. These results demonstrate the advantages of the multi-layer device architecture over the conventional 2-layer structure.

APA, Harvard, Vancouver, ISO, and other styles

17

Chhaya, Lipi K., Paawan Sharma, Adesh Kumar, and Govind Bhagwatikar. "Cross Layer Optimization and Simulation of Smart Grid Home Area Network." Modelling and Simulation in Engineering 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/3561739.

Full text

Abstract:

An electrical “Grid” is a network that carries electricity from power plants to customer premises. Smart Grid is an assimilation of electrical and communication infrastructure. Smart Grid is characterized by bidirectional flow of electricity and information. Smart Grid is a complex network with hierarchical architecture. Realization of complete Smart Grid architecture necessitates diverse set of communication standards and protocols. Communication network protocols are engineered and established on the basis of layered approach. Each layer is designed to produce an explicit functionality in association with other layers. Layered approach can be modified with cross layer approach for performance enhancement. Complex and heterogeneous architecture of Smart Grid demands a deviation from primitive approach and reworking of an innovative approach. This paper describes a joint or cross layer optimization of Smart Grid home/building area network based on IEEE 802.11 standard using RIVERBED OPNET network design and simulation tool. The network performance can be improved by selecting various parameters pertaining to different layers. Simulation results are obtained for various parameters such as WLAN throughput, delay, media access delay, and retransmission attempts. The graphical results show that various parameters have divergent effects on network performance. For example, frame aggregation decreases overall delay but the network throughput is also reduced. To prevail over this effect, frame aggregation is used in combination with RTS and fragmentation mechanisms. The results show that this combination notably improves network performance. Higher value of buffer size considerably increases throughput but the delay is also greater and thus the choice of optimum value of buffer size is inevitable for network performance optimization. Parameter optimization significantly enhances the performance of a designed network. This paper is expected to serve as a comprehensive analysis and performance enhancement of communication standard suitable for Smart Grid HAN applications.

APA, Harvard, Vancouver, ISO, and other styles

18

Zhang, Xiaodong, Ming Gong, Junfeng Pan, Mingxin Song, Hang Zhang, and Linlin Zhang. "Simulation Study of Low Turn-Off Loss and Snapback-Free SA-IGBT with Injection-Enhanced p-Floating Layer." Electronics 11, no. 15 (July 28, 2022): 2351. http://dx.doi.org/10.3390/electronics11152351.

Full text

Abstract:

In this study, a shorted-anode IGBT with an injection-enhanced p-floating layer (IEPF-IGBT) under the N-buffer layer is proposed. Compared to conventional shorted-anode IGBT (SA-IGBT), the IEPF-IGBT has the structural characteristics of an injection-enhanced P-floating (IEPF) layer inserted into the N-buffer layer and the P+ collector region. The IEPF layer and P+ collector region pinch off the electron path during the turn-on period to suppress the snapback effect with a half-cell pitch of 10 μm. In addition, the IEPF layer acts as an injection-enhanced layer that influences the current injection of the holes. There is 56.3% reduction in the turn-off loss of the IEPF-IGBT at the same forward voltage drop.

APA, Harvard, Vancouver, ISO, and other styles

19

Shim, Hyotaek, Dawoon Jung, Jaegeuk Kim, Jin-Soo Kim, and Seungryoul Maeng. "Co-optimization of buffer layer and FTL in high-performance flash-based storage systems." Design Automation for Embedded Systems 14, no. 4 (November 4, 2010): 415–43. http://dx.doi.org/10.1007/s10617-010-9066-y.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Zhao, Tianshuo, Earl D. Goodwin, Jiacen Guo, Han Wang, Benjamin T. Diroll, Christopher B. Murray, and Cherie R. Kagan. "Advanced Architecture for Colloidal PbS Quantum Dot Solar Cells Exploiting a CdSe Quantum Dot Buffer Layer." ACS Nano 10, no. 10 (September 22, 2016): 9267–73. http://dx.doi.org/10.1021/acsnano.6b03175.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Celentano, G., V. Boffa, L. Ciontea, F. Fabbri, V. Galluzzi, U. Gambardella, A. Mancini, et al. "High Jc YBCO coated conductors on non-magnetic metallic substrate using YSZ-based buffer layer architecture." Physica C: Superconductivity 372-376 (August 2002): 790–93. http://dx.doi.org/10.1016/s0921-4534(02)00908-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Trommler, S., R. Hühne, J. Hänisch, E. Reich, K. Iida, S. Haindl, V. Matias, L. Schultz, and B. Holzapfel. "The influence of the buffer layer architecture on transport properties for BaFe1.8Co0.2As2 films on technical substrates." Applied Physics Letters 100, no. 12 (March 19, 2012): 122602. http://dx.doi.org/10.1063/1.3696888.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Polat, O., T. Aytug, M. Paranthaman, K. Kim, Y. Zhang, J. R. Thompson, D. K. Christen, X. Xiong, and V. Selvamanickam. "Direct growth of LaMnO3 cap buffer layers on ion-beam-assisted deposition MgO for simplified template-based YBa2Cu3O7−δ-coated conductors." Journal of Materials Research 23, no. 11 (November 2008): 3021–28. http://dx.doi.org/10.1557/jmr.2008.0362.

Full text

Abstract:

Simplification of the ion-beam-assisted deposition (IBAD) buffer architecture is one of the key issues for reduced manufacturing cost of second-generation superconducting wire production. In this work, we studied various radio frequency magnetron sputter deposition conditions for epitaxial growth of LaMnO3 (LMO) layers, with varying thicknesses, directly on IBAD-MgO without homo-epitaxial MgO layers. Performance of the simplified LMO/IBAD-MgO samples was qualified by pulsed-laser-deposited 1-μm-thick YBa2Cu3O7−δ (YBCO) coatings. Detailed property characterizations revealed that though the growth temperature has a substantial effect on the texture of LMO layers, neither LMO thickness nor different sputter gas compositions had a significant effect on the performance of YBCO films. The superconducting properties of YBCO on LMO/IBAD-MgO are found to be similar to those obtained on templates having homo-epitaxial MgO layers. The present results underscore the strong potential of LMO as a single cap layer directly on IBAD-MgO for the development of a simplified IBAD architecture.

APA, Harvard, Vancouver, ISO, and other styles

24

Islam, Md Tanvirul, Tedi Kujofsa, Xinkang Chen, and J. E. Ayers. "Threading Dislocation Behavior in InGaAs/GaAs (001) Superlattice Buffer Layers." International Journal of High Speed Electronics and Systems 28, no. 03n04 (September 2019): 1940017. http://dx.doi.org/10.1142/s0129156419400172.

Full text

Abstract:

We conducted a modeling study of the threading dislocation behavior in chirped and unchirped InGaAs/GaAs (001) strained-layer superlattices (SLSs) using a Dodson & Tsao / Kujofsa & Ayers (DTKA) type plastic flow model. Four types of SLSs were investigated: type I was chirped using compositional modulation, type II was chirped using layer thickness modulation, type III was unchirped with alternating layers of InGaAs and GaAs, and type IV was unchirped with alternating layers of InGaAs having two different compositions. Generally the surface and average values of the dislocation density decreased with increasing total thickness. The dependence on top indium composition was more complex, due to dislocation compensation and multiplication effects, but for type II and IV superlattices, the average and surface threading dislocation densities increased in nearly monotonic fashion with top indium composition. Based on these results, the compositionally-modulated chirped (type I) and InGaAs/GaAs unchirped (type III) superlattices appear to be best suited as buffer layers for metamorphic devices, while the chirped superlattices with layer thickness modulation (type II) and InGaAs/InGaAs unchirped (type IV) superlattices appear to be poorly suited for use as buffer layers for devices containing high indium content.

APA, Harvard, Vancouver, ISO, and other styles

25

KIM, HONG KOO, and NASIR ABDUL BASIT. "FERROELECTRIC NONVOLATILE MEMORY FIELD-EFFECT TRANSISTORS BASED ON A NOVEL BUFFER LAYER STRUCTURE." International Journal of High Speed Electronics and Systems 10, no. 01 (March 2000): 39–46. http://dx.doi.org/10.1142/s0129156400000076.

Full text

Abstract:

We have proposed and developed a ferroelectric nonvolatile field-effect transistor that incorporates a thin MgO buffer layer between a ferroelectric film and an oxidized Si substrate. The use of an MgO/SiO2 buffer for a ferroelectric gate is based on the following findings. First, a thin MgO buffer serves well as a template layer allowing the growth of highly oriented ferroelectric films on amorphous substrates. Second, MgO works well as a diffusion barrier between a ferroelectric film and a substrate, protecting the silicon FET channel region from interdiffusion or reaction that may occur during device processing. Third, thermal oxidation of Si is known to be one of the best ways of passivating silicon surfaces, thus to reduce high quality FET channels. The fabricated devices show excellent performance in ferroelectric polarization switching, memory retention, and fatigue resistance. The devices also demonstrate scalability in device dimension and operating voltage, i.e., they are suitable for low voltage operation (3-5 V or below) showing a sufficient memory window (1-2 V).

APA, Harvard, Vancouver, ISO, and other styles

26

Cantoni, C., D. K. Christen, M. Varela, J. R. Thompson, S. J. Pennycook, E. D. Specht, and A. Goyal. "Deposition and characterization of YBa2Cu3O7−δ/LaMnO3/MgO/TiN heterostructures on Cu metal substrates for development of coated conductors." Journal of Materials Research 18, no. 10 (October 2003): 2387–400. http://dx.doi.org/10.1557/jmr.2003.0334.

Full text

Abstract:

In this paper a novel buffer layer architecture consisting of LaMnO3/MgO/TiN is proposed as a suitable structural and chemical template for the epitaxial growth of high-transition temperature (Tc) superconductors on Cu metal surfaces. Using techniques such as high-energy electron diffraction and scanning transmission electron microscopy, we present in situ and ex situ analyses of the buffer-layer and superconductor growth with focus on structural properties of the interfaces formed. While MgO is a good barrier to oxygen diffusion, we find that MgO alone is not a suitable buffer layer due to rapid Cu diffusion. Further, growth of MgO with a single epitaxy can be hindered by the presence of impurities such as S, which form strongly bonded superstructures on the metal surface. With the addition of a TiN layer as a barrier to Cu diffusion, oxide formation is suppressed, interfaces are clean, and a single cube-on-cube epitaxy is observed. While the Cu/TiN and TiN/MgO interfaces are rough, the MgO and LaMnO3 layers planarize the material, leading to growth of smooth YBa2Cu3O7−δ (YBCO). Residual strain in the YBCO film is 0.25% or less and does not lead to apparent cracking. The superconducting properties of the samples were investigated by electrical transport and magnetization measurements. For the first time, high critical current density (Jc) values are reported for YBCO films grown on (001) single-crystal and 100‹100›?textured Cu surfaces without intervening metal coatings. Jc on single crystal-like substrates is as high as 3.5 MA/cm2. Reduced Jc of approximately 1 MA/cm2 on rolled Cu tapes is limited by damage to the tape surface during the rolling process.

APA, Harvard, Vancouver, ISO, and other styles

27

Predeep, P., T. A. Shahul Hameed, J. Aneesh, and M. R. Baiju. "Organic Light Emitting Diodes: Effect of Annealing the Hole Injection Layer on the Electrical and Optical Properties." Solid State Phenomena 171 (May 2011): 39–50. http://dx.doi.org/10.4028/www.scientific.net/ssp.171.39.

Full text

Abstract:

Organic Light Emitting Diodes (OLED) are receiving increased attention due to tremendous application potential these devices hold in the areas of large area displays and lighting applications. However, the problems of efficiency, stability and shelf life are major challenges for making OLEDs an attractive alternative. The simple device structure involving anode, emissive layer and cathode is no longer the norm. Recently, various buffer layers like Hole Injection Layer (HIL), Hole transport Layer (HTL), Electron Injection Layer (EIL), Electron Transport Layer (ETL) etc. are being widely used as integral parts of the OLED architecture to enhance the performance parameters. The nomenclature of these layers is often confusing and sometimes used by different authors to mean different layers and a common and universal nomenclature for layers is still wanting. Applying a buffer layer, often called as the hole injecting layer (HIL) between anode and emissive layer is a general technique for increasing the efficiency and stability of organic light emitting diodes. Poly- (3,4-ethyhylene dioxythiophene): poly- (styrenesulphonate) (PEDOT:PSS) is a very common and popular such HIL used in OLEDs. In this chapter, a basic structure of OLEDs has been discussed in perspective with this HIL material and the effect of annealing this PEDOT: PSS layer on the characteristics of the device at different temperatures ranging from 100°C to 300°C in vacuum. Devices fabricated in clean room conditions are characterized for their electrical and optical properties. Equivalent circuits of the devices are deduced using impedance spectroscopy and discussed. Surface morphology of the HIL layers using atomic force microscopy (AFM) provides reasons for the variation of the device properties with the annealing of HIL.

APA, Harvard, Vancouver, ISO, and other styles

28

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

29

Habashy, Rober, Mouhamad Khoder, Abdullah Isreb, and Mohamed A. Alhnan. "A Novel Multilayer Natural Coating for Fed-State Gastric Protection." Pharmaceutics 14, no. 2 (January 26, 2022): 283. http://dx.doi.org/10.3390/pharmaceutics14020283.

Full text

Abstract:

Several nutraceutical products require gastric protection against the hostile environment in the stomach. Currently marketed synthetic and semi-synthetic coatings suffer from major shortcomings such as poor gastric protection, slow-release response to pH change, and the use of artificial ingredients. The challenge of coating natural products is further exacerbated by the relatively high gastric pH in the fed state. In this work, a novel natural enteric coating is presented as a breakthrough alternative to current solutions. Two coating systems were devised: (i) a triple-layer coating that comprises a wax layer embedded between two alginate-based coatings, and (ii) a double-layer coating, where an overcoat of organic acids (fumaric or citric acid) is applied to an alginate-based coating. The multi-layer architecture did not impact the pH-responsive nature of the coating even when more biologically relevant Krebs bicarbonate buffer of lower buffer capacity was used. Interestingly, the gastric protection barrier of organic acid-based coating remained resistant at elevated gastric pH 2, 3, or 4 for 2 h. This is the first report of using an alginate-based coating to provide gastric protection against fed-state stomach conditions (pH 2–4). Being biodegradable, naturally occurring, and with no limit on daily intake, the reported novel coating provides a superior platform to current coating solutions for pharmaceutical and nutraceutical products.

APA, Harvard, Vancouver, ISO, and other styles

30

Mohammed, Hussaim, M. M. A. Hashem, and Palash Gupta. "AN EFFICIENT PACKET SCHEDULING ALGORITHM FOR 4G IP-BASED MOBILE NETWORKS." IIUM Engineering Journal 10, no. 1 (September 29, 2010): 31–48. http://dx.doi.org/10.31436/iiumej.v10i1.103.

Full text

Abstract:

Next generation mobile networks are expected to provide seamless personal mobile communication and quality of service (QoS). Lossless handoff is a key issue for providing the QoS. This paper presents 4G node B Architecture, a two-layer downlink queuing model and proposes a scheduling mechanism for providing lossless handoff and QoS in mobile networks, which exploit IP as a transport technology for transferring datagrams between base stations and the high-speed downlink packet access (HSDPA) at the radio layer. In order to reduce handoff packet dropping rate at the radio layer and packet forwarding rate at the IP layer and to provide high system performance, new scheduling algorithms are performed at both IP and radio layer, which exploit handoff priority scheduling principles and take into account buffer occupancy and channel conditions. Performance results obtained by computer simulation show that, by exploiting the downlink queuing model and scheduling algorithms, the system is able to provide low handoff packet dropping rate, low packet forwarding rate, and high downlink throughput.

APA, Harvard, Vancouver, ISO, and other styles

31

Al-Obeidi, Ahmed, Chenhao Ge, Kristina S. Orosz, and S. Scott Saavedra. "ITO/Poly(Aniline)/Sol-Gel Glass: An Optically Transparent, pH-Responsive Substrate for Supported Lipid Bilayers." Journal of Materials 2013 (March 30, 2013): 1–6. http://dx.doi.org/10.1155/2013/676920.

Full text

Abstract:

Described here is fabrication of a pH-sensitive, optically transparent transducer composed of a planar indium-tin oxide (ITO) electrode overcoated with a poly(aniline) (PANI) thin film and a porous sol-gel layer. Adsorption of the PANI film renders the ITO electrode sensitive to pH, whereas the sol-gel spin-coated layer makes the upper surface compatible with fusion of phospholipid vesicles to form a planar supported lipid bilayer (PSLB). The response to changes in the pH of the buffer contacting the sol-gel/PANI/ITO electrode is pseudo-Nernstian with a slope of 52 mV/pH over a pH range of 4–9. Vesicle fusion forms a laterally continuous PSLB on the upper sol-gel surface that is fluid with a lateral lipid diffusion coefficient of 2.2 μm2/s measured by fluorescence recovery after photobleaching. Due to its lateral continuity and lack of defects, the PSLB blocks the pH response of the underlying electrode to changes in the pH of the overlying buffer. This architecture is simpler to fabricate than previously reported ITO electrodes derivatized for PSLB formation and should be useful for optical monitoring of proton transport across supported membranes derivatized with ionophores and ion channels.

APA, Harvard, Vancouver, ISO, and other styles

32

Vannozzi, A., V. Galluzzi, A. Mancini, A. Rufolini, A. Augieri, A. Angrisani Armenio, L. Ciontea, Gy Thalmaier, T. Petrisor, and G. Celentano. "Study of MgO-Based Buffer Layer Architecture for the Development of Ni–Cu-Based RABiTS YBCO Coated Conductor." IEEE Transactions on Applied Superconductivity 21, no. 3 (June 2011): 2908–11. http://dx.doi.org/10.1109/tasc.2010.2081331.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Jiménez, C., T. Caroff, A. Bartasyte, S. Margueron, A. Abrutis, O. Chaix-Pluchery, and F. Weiss. "Raman Study of CeO2 Texture as a Buffer Layer in the CeO2/La2Zr2O7/Ni Architecture for Coated Conductors." Applied Spectroscopy 63, no. 4 (April 2009): 401–6. http://dx.doi.org/10.1366/000370209787944334.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Luzuriaga, Jorge E., Miguel Perez, Pablo Boronat, Juan Carlos Cano, Carlos Calafate, and Pietro Manzoni. "Improving MQTT Data Delivery in Mobile Scenarios: Results from a Realistic Testbed." Mobile Information Systems 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/4015625.

Full text

Abstract:

MQTT is being widely used for data delivery in IoT applications but its architecture does not properly handle mobility when disconnection periods tend to be large. In this paper we describe an experimental evaluation, made in a real environment, of a solution that guarantees that there is no information loss when variable length hand-offs appear due to the movement of a node. Our proposal modifies the classical publish/subscribe scheme by introducing an intermediate buffer that takes care of message transfer. Finally, we study the impact related to the connectivity of mobile devices of the use of the standard LinuxNetwork Manager. We propose a cross-layer solution that improves the device connectivity in conjunction with the data layer management. We show that our solution improves the data delivery guaranteeing that no information is lost.

APA, Harvard, Vancouver, ISO, and other styles

35

Knipper, Martin, Jürgen Parisi, Kevin Coakley, Christoph Waldauf, Christoph J. Brabec, and Vladimir Dyakonov. "Impedance Spectroscopy on Polymer-Fullerene Solar Cells." Zeitschrift für Naturforschung A 62, no. 9 (September 1, 2007): 490–94. http://dx.doi.org/10.1515/zna-2007-0904.

Full text

Abstract:

Impedance spectroscopy is used for studying the electrical transport properties of bulk heterojunction solar cells. A replacement circuit is needed to translate the frequency response of the circuit to the individual interfaces and layers of the solar cell. As a material combination and device architecture, composites of P3HT and PCBM, sandwiched between a transparent ITO front electrode and an aluminum back electrode, as well as a polymer buffer layer were investigated. By varying the film thickness we identified an equivalent circuit capable to fit our experimental data. We found a dielectric constant for the P3HT and for the P3HT:PCBM bulk.

APA, Harvard, Vancouver, ISO, and other styles

36

Hu, Chao-Chang, Shih-Yi Wen, Chen-Peng Hsu, Chun-Wei Chang, Chih-Tsung Shih, and Hsiao-Wen Lee. "Solder bonding with a buffer layer for MOEMS packaging using induction heating." Microsystem Technologies 12, no. 10-11 (April 6, 2006): 1011–14. http://dx.doi.org/10.1007/s00542-006-0147-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Holesinger, T. G., S. R. Foltyn, P. N. Arendt, H. Kung, Q. X. Jia, R. M. Dickerson, P. C. Dowden, R. F. DePaula, J. R. Groves, and J. Y. Coulter. "The microstructure of continuously processed Yba2Cu3Oy coated conductors with underlying CeO2 and ion-beam-assisted yttria-stabilized zirconia buffer layers." Journal of Materials Research 15, no. 5 (May 2000): 1110–19. http://dx.doi.org/10.1557/jmr.2000.0158.

Full text

Abstract:

The microstructural development of YBa2Cu3Oy (Y-123) coated conductors based on the ion-beam-assisted deposition (IBAD) of yttria-stabilized zirconia (YSZ) to produce a biaxially textured template is presented. The architecture of the conductors was Y-123/CeO2/IBAD YSZ/Inconel 625. A continuous and passivating Cr2O3 layer forms between the YSZ layer and the Inconel substrate. CeO2 and Y-123 are closely lattice-matched, and misfit strain is accommodated at the YSZ/CeO2 interface. Localized reactions between the Y-123 film and the CeO2 buffer layer result in the formation of BaCeO3, YCuO2, and CuO. The positive volume change that occurs from the interfacial reaction may act as a kinetic barrier that limits the extent of the reaction. Excess copper and yttrium generated by the interfacial reaction appear to diffuse along grain boundaries and intercalate into Y-123 grains as single layers of the Y-247, Y-248, or Y-224 phases. The interfacial reactions do not preclude the attainment of high critical currents (Ic) and current densities (Jc) in these films nor do they affect to any appreciable extent the nucleation and alignment of the Y-123 film.

APA, Harvard, Vancouver, ISO, and other styles

38

Islam, Md Tanvirul, Xinkang Chen, Tedi Kujofsa, and John E. Ayers. "Threading Dislocations in Metamorphic Semiconductor Buffer Layers Containing Chirped Superlattices." International Journal of High Speed Electronics and Systems 27, no. 03n04 (September 2018): 1840028. http://dx.doi.org/10.1142/s0129156418400281.

Full text

Abstract:

Metamorphic realization of semiconductor devices has become increasingly important due to the great freedom it affords in layer compositions and thicknesses. However, metamorphic growth is often accompanied by the introduction of high densities of threading dislocation defects. This behavior may be understood by using an annihilation and coalescence model for the threading dislocation behavior which is based on the dislocation interaction length Lint. For its application we considered only glide of dislocations, so the interaction length was assumed to be equal to the length of misfit dislocation segments LMD. The length of misfit segments was determined approximately by the Matthews, Mader, and Light model [J. Appl. Phys., 41, 3800 (1970)] for lattice relaxation, and was assumed to be independent of the distance from the interface. Within this framework we have applied the annihilation and coalescence model to chirped semiconductor superlattices to evaluate these superlattices as strainrelaxed buffers for metamorphic devices. In this work we have studied two basic types of InGaAs/GaAs chirped superlattice buffers: type I superlattices are compositionally modulated while type II superlattices are thickness modulated.

APA, Harvard, Vancouver, ISO, and other styles

39

Arredondo-Velázquez, Moisés, Paulo Aaron Aguirre-Álvarez, Alfredo Padilla-Medina, Alejandro Espinosa-Calderon, Juan Prado-Olivarez, and Javier Diaz-Carmona. "Flexible Convolver for Convolutional Neural Networks Deployment onto Hardware-Oriented Applications." Applied Sciences 13, no. 1 (December 21, 2022): 93. http://dx.doi.org/10.3390/app13010093.

Full text

Abstract:

This paper introduces a flexible convolver capable of adapting to the different convolution layer configurations of state-of-the-art Convolution Neural Networks (CNNs). The use of two proposed programmable components achieves this adaptability. A Programmable Line Buffer (PLB) based on Programmable Shift Registers (PSRs) allows the generation of the required convolution masks required for each processed CNN layer. The convolution layer computing is performed through a proposed programmable systolic array configured according to the target device resources. In order to maximize the device resource usage and to achieve a shortened processing time, the filter, data, and loop parallelisms are leveraged. These characteristics allow the described architecture to be scalable and implemented on any FPGA device targeting different applications. The convolver description was written in VHDL using the Intel Cyclone V 5CSXFC6D6F31C6N device as a reference. The experimental results show that the proposed computing method allows the processing of any CNN without requiring special adaptation for a specific application since the standard convolution algorithm is used. The proposed flexible convolver achieves competitive performance compared with those reported in related works.

APA, Harvard, Vancouver, ISO, and other styles

40

Huang, Yan Qin. "Preparation of Epitaxial YBa₂Cu₃O_7−y Films and CeO₂ Buffer Layer on Ni-5at.%W Substrates by MOD Method." Advanced Materials Research 538-541 (June 2012): 64–67. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.64.

Full text

Abstract:

Biaxially textured CeO2 films were deposited on Ni–5at.%W (Ni–5W) tapes by a metal-organic deposition (MOD) method. Subsequent YBa2Cu3O7-y (YBCO) films were prepared using the (MOD) method leading to a simplified coated conductor architecture of YBCO/CeO2/Ni–5W. X-ray diffraction measurements revealed an epitaxial growth of the CeO2 buffer layer the 7.06°, 5.16°, for the out-of-plane and in-plane alignment, respectively. The superconducting coated film with a texture spread down to the out-of-plane texture is ω = 6.2° and the in-plane texture is φ = 7.6°. The results indicate that single CeO2-buffered Ni–5W tapes are suitable for the epitaxial growth of YBCO higher cube texture and the epitaxial YBCO film was obtained. To microstructural investigations, the film’s SEM results showed a dense, smooth and crack-free surface morphology. The superconducting properties were measured by four probe method. The superconducting transition temperature (Tc) was about 90 K with a narrow transition of 0.8 K and the critical current density (Jc) was about 1.5×104 A/cm2 at 77 K, 4T.

APA, Harvard, Vancouver, ISO, and other styles

41

Stergiou, Eleftherios, John Garofalakis, Dimitrios Liarokapis, and Spiridoula Margariti. "Investigating Multilayer Omega-Type Networks Operating with the Cut-Through Technique under Uniform or Hotspot Traffic Conditions." International journal of Computer Networks & Communications 13, no. 5 (September 30, 2021): 89–109. http://dx.doi.org/10.5121/ijcnc.2021.13506.

Full text

Abstract:

The continuous increase in the complexity of data networks has motivated the development of more effective Multistage Interconnection Networks (MINs) as important factors in providing higher data transfer rates in various switching divisions. In this paper, semi-layer omega-class networks operating with a cut-through forwarding technique are chosen as test-bed subjects for detailed evaluation, and this network architecture is modelled, inspected, and simulated. The results are examined for relevant singlelayer omega networks operating with cut-through or ‘store and forward’ forwarding techniques. Two series of experiments are carried out: one concerns the case of uniform traffic, while the other is related to hotspot traffic. The results quantify the way in which this network outperforms the corresponding singlelayer network architectures for the same network size and buffer size. Furthermore, the effects of the dimensions of the switch elements and their corresponding reliability on the overall interconnection system are investigated, and the complexity and the relevant cost are examined. The data yielded by this investigation can be valuable to MIN engineers and can allow them to achieve more productive networks with lower overall implementation costs.

APA, Harvard, Vancouver, ISO, and other styles

42

Boukortt, Nour El I., Salvatore Patanè, Baghdad Hadri, and Giovanni Crupi. "Graded Bandgap Ultrathin CIGS Solar Cells (Invited Paper)." Electronics 12, no. 2 (January 12, 2023): 393. http://dx.doi.org/10.3390/electronics12020393.

Full text

Abstract:

In this paper, we physically modeled passivated ultrathin Cu (In1−xGax) Se2 solar cells with different bandgap grading configurations. Firstly, we have designed the cell architecture according to the fabricated model. The novelty in this work is the modeling of passivated u-CIGS solar cells with different bandgap grading profile configurations in order to achieve high efficiency with a thickness of 500 nm. A significant influence on device performance has been observed while changing absorber doping density, electron affinity, and operating temperature (range of 10–70 °C) for the investigated samples. ZnS has been used as a buffer layer to replace the conventional CdS material in order to improve cell efficiency. The impact of the buffer doping density and electron affinity on u-CIGS cell performance is explored. The simulation results show that a high bandgap at the front and rear sides with an acceptor density of 2 × 1016 provide the best electrical cell parameters: Jsc of 31.53 mA/cm2, Voc of 742.78 mV, FF of 77.50%, η of 18.15%. Our findings can be considered guidelines for new single and/or tandem cell optimization to achieve high efficiency.

APA, Harvard, Vancouver, ISO, and other styles

43

Liu, Yi-Jung, Tsung-Yuan Tsai, Kuo-Hui Yu, Der-Feng Guo, Li-Yang Chen, Tsung-Han Tsai, and Wen-Chau Liu. "A low damage GaN-based light-emitting diode with textured/inclined sidewalls and an air–buffer layer." Displays 31, no. 2 (April 2010): 111–14. http://dx.doi.org/10.1016/j.displa.2010.02.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Shobih, Shobih, Rizky Abdillah, and Erlyta Septa Rosa. "Fabrication of Hybrid Polymer Solar Cells By Inverted Structure Based on P3HT:PCBM Active Layer." Jurnal Elektronika dan Telekomunikasi 17, no. 1 (August 31, 2017): 13. http://dx.doi.org/10.14203/jet.v17.13-18.

Full text

Abstract:

Hybrid polymer solar cell has privilege than its conventional structure, where it usually has structure of (ITO/PEDOT:PSS/Active Layer/Al). In humid environment the PEDOT:PSS will absorb water and hence can easily etch the ITO. Therefore it is necessary to use an alternative method to avoid this drawback and obtain more stable polymer solar cells, namely by using hybrid polymer solar cells structure with an inverted device architecture from the conventional, by reversing the nature of charge collection. In this paper we report the results of the fabrication of inverted bulk heterojunction polymer solar cells based on P3HT:PCBM as active layer, utilizing ZnO interlayer as buffer layer between the ITO and active layer with a stacked structure of ITO/ZnO/P3HT:PCBM/PEDOT:PSS/Ag. The ZnO interlayer is formed through short route, i.e. by dissolving ZnO nanoparticles powder in chloroform-methanol solvent blend rather than by sol-gel process. Based on the measurement results on electrical characteristics of inverted polymer solar cells under 500 W/m2 illumination and AM 1.5 direct filter at room temperature, cell with annealing process of active layer at 110 °C for 10 minutes results in higher cell performance than without annealing, with an open-circuit voltage of 0.21 volt, a short-circuit current density of 1.33 mA/cm2 , a fill factor of 43.1%, and a power conversion efficiency of 0.22%. The low cell’s performance is caused by very rough surface of ZnO interlayer.

APA, Harvard, Vancouver, ISO, and other styles

45

Apicella, M. L., V. Boffa, G. Celentano, F. Fabbri, and T. Petrisor. "The Effects of Surface Contamination on the Biaxially Textured Substrate for YBCO Thick Film Deposition." International Journal of Modern Physics B 13, no. 09n10 (April 20, 1999): 997–1004. http://dx.doi.org/10.1142/s0217979299000850.

Full text

Abstract:

The epitaxial growth of YBa 2 Cu 3 O 7-x (YBCO) films on biaxially textured substrates is one of the most promising technique for the fabrication of high current superconducting tapes operating at high temperature. Ni is very attractive as substrate because it easily develops a (100)[001] cubic texture. The low oxidation resistance represents the main drawback of the Ni substrate. In order to better assess the role of oxygen on the Ni substrates, a surface physics technique as Auger spectroscopy has been used. It has allowed to evaluate the amount of impurities for different Ni processing and exposure to the air. The results demonstrate that the surface contamination can be efficiently removed by RF sputtering before buffer layer deposition. This procedure allows to obtain CeO 2/Pd/Ni architecture by laser ablation with a good epitaxy both of Pd and CeO 2 films. On the contrary, when CeO 2 is directly deposited on Ni a low epitaxy is obtained. The Auger analysis confirms that the formation of (111) NiO at the Ni - CeO 2 interface hampers the epitaxial growth of the ceria film.

APA, Harvard, Vancouver, ISO, and other styles

46

Chen, Yingwen, Hujie Yu, Bowen Hu, Zhimin Duan, and Guangtao Xue. "An Edge Caching Strategy Based on User Speed and Content Popularity for Mobile Video Streaming." Electronics 10, no. 18 (September 10, 2021): 2217. http://dx.doi.org/10.3390/electronics10182217.

Full text

Abstract:

Mobile users’ demands to delay-sensitive video streaming media put forward new requirements for mobile networks, such as architecture optimization. Edge caching as a new paradigm is proposed to enhance the quality of service (QoS) for mobile users at the network edge. Due to the limited coverage of edge cache nodes, the frequent handoffs between base stations would aggravate network traffic overhead, resulting in a bad experience of high latency and service interruption when mobile users browse videos. This paper first proposes a three-layer mobile edge network architecture and applied edge caching to video streams to build an efficient caching system. Given the user’s mobility and low latency of mobile video streaming, we propose an edge caching strategy based on user speed and content popularity. Horizontally, the user’s speed affects the spanning area and the buffer size of the cache on edge; vertically, content popularity determines the priority of cached videos. Experimental results demonstrate that our caching strategy outperforms other schemes in terms of the average delay and the cache hit ratio in mobile video streaming scenes compared with the other three classic caching methods.

APA, Harvard, Vancouver, ISO, and other styles

47

Sathyamurthy, Srivatsan, Mariappan Paranthaman, Lee Heatherly, Patrick M. Martin, E. D. Specht, Amit Goyal, Thomas Kodenkandath, Xiaoping Li, and Martin W. Rupich. "Solution-processed lanthanum zirconium oxide as a barrier layer for high Ic-coated conductors." Journal of Materials Research 21, no. 4 (April 1, 2006): 910–14. http://dx.doi.org/10.1557/jmr.2006.0112.

Full text

Abstract:

High-quality lanthanum zirconium oxide (La2Zr2O7 or LZO) films have been deposited and processed on Ni–W substrates using a sol-gel processing approach. It has been demonstrated that crack-free coatings with thicknesses up to 100 nm can be processed in a single step, while thicker coatings (200–225 nm) were processed using a multiple coating and annealing process. Using simulated metalorganic deposition (MOD)-YBa2Cu3O7−δ (YBCO) processing conditions, the barrier properties of the sol-gel LZO coating with a thickness of 120 nm were found to be comparable to that of the standard 3-layer buffer stack deposited using physical vapor deposition. Secondary ion mass spectroscopy depth profile analysis of LZO films annealed in oxygen-18 shows that LZO effectively stops the diffusion of Ni within the first 80–100 nm. Using MOD processes, a CeO2 cap layer and superconducting YBCO layer were deposited on sol-gel LZO/Ni–W. For the first time, using such an all-solution conductor architecture, a critical current (Ic) of 140 A/cm with a corresponding critical current density (Jc) of 1.75 MA/cm2 has been demonstrated. Using a very thin Y2O3 seed layer (∼10 nm) deposited by electron beam evaporation; improved texture quality in the LZO layers has been demonstrated. The performance of the LZO deposited on these samples was evaluated using a sputtered CeO2 cap layer and MOD YBCO layer. Critical currents of up to 255 A/cm (3.2 MA/cm2) with 0.8-μm-thick YBCO films have been demonstrated, comparable to the performance of films grown using physical vapor deposited yttria stabilized zirconia as a barrier layer. Similar experiments using an MOD-CeO2 cap layer and MOD-YBCO layer yielded critical currents of 200 A/cm (2.5 MA/cm2) with 0.8-μm-thick YBCO films.

APA, Harvard, Vancouver, ISO, and other styles

48

Gago, Raúl, Slawomir Prucnal, René Hübner, Frans Munnik, David Esteban-Mendoza, Ignacio Jiménez, and Javier Palomares. "Phase Selectivity in Cr and N Co-Doped TiO2 Films by Modulated Sputter Growth and Post-Deposition Flash-Lamp-Annealing." Coatings 9, no. 7 (July 17, 2019): 448. http://dx.doi.org/10.3390/coatings9070448.

Full text

Abstract:

In this paper, we report on the phase selectivity in Cr and N co-doped TiO2 (TiO2:Cr,N) sputtered films by means of interface engineering. In particular, monolithic TiO2:Cr,N films produced by continuous growth conditions result in the formation of a mixed-phase oxide with dominant rutile character. On the contrary, modulated growth by starting with a single-phase anatase TiO2:N buffer layer, can be used to imprint the anatase structure to a subsequent TiO2:Cr,N layer. The robustness of the process with respect to the growth conditions has also been investigated, especially regarding the maximum Cr content (<5 at.%) for single-phase anatase formation. Furthermore, post-deposition flash-lamp-annealing (FLA) in modulated coatings was used to improve the as-grown anatase TiO2:Cr,N phase, as well as to induce dopant activation (N substitutional sites) and diffusion. In this way, Cr can be distributed through the whole film thickness from an initial modulated architecture while preserving the structural phase. Hence, the combination of interface engineering and millisecond-range-FLA opens new opportunities for tailoring the structure of TiO2-based functional materials.

APA, Harvard, Vancouver, ISO, and other styles

49

Yoo, J., K. J. Leonard, D. F. Lee, H. S. Hsu, L. Heatherly, F. A. List, N. A. Rutter, A. Goyal, M. Paranthaman, and D. M. Kroeger. "Effects of Conversion Parameters on the Transport Properties of YBCO Films in the BaF2 Ex Situ Process." Journal of Materials Research 19, no. 4 (April 2004): 1281–89. http://dx.doi.org/10.1557/jmr.2004.0166.

Full text

Abstract:

The effects of conversion parameters on transport properties of YBa2Cu3O7-δ (YBCO) films on rolling assisted biaxially textured substrates (RABiTS) in the BaF2 ex situ process were investigated for total pressures Ptotal between 0.1 and 1.3 atm, water vapor pressures PH2O between approximately 7 and 70 Torr and processing temperatures TS between 700 and 790 °C. For this study, a 0.3-μm-thick Y–BaF2–Cu–O precursor film was deposited on a 1-cm-wide Ni=3 at.% W RABiTS with a buffer layer architecture of CeO2/YSZ/Y2O3/Ni deposited in single passes in various reel-to-reel systems for each layer. Under the conditions of Ptotal = 0.1 atm, TS = 740 °C and PO2 approximately 150 mTorr, JC > 2 MA/cm2 was obtained at 77 K and self field for PH2O ≤ 20 Torr. At higher PH2O (=70 Torr), however, the maximum attainable JC decreased. In addition, the JC at these higher PH2O dropped rapidly with increased dwell time. The highest JC, 2.5 MA/cm2, was achieved at 730 °C with Ptotal = 0.1 atm and PH2O approximately 7 Torr. Finally, the variation of IC with wet conversion time was performed at each processing temperature.

APA, Harvard, Vancouver, ISO, and other styles

50

Gilioli, E., Andrea Gauzzi, Massimiliano Bindi, S. Rampino, F. Pattini, F. Bissoli, Stefano Ginocchio, M. Baldini, and Sergio Zannella. "Progress in the Continuous Depostition of YBCO Coated Conductors by Thermal Co-Evaporation." Advances in Science and Technology 47 (October 2006): 17–24. http://dx.doi.org/10.4028/www.scientific.net/ast.47.17.

Full text

Abstract:

We report on recent progress towards the continuous deposition of YBCO Coated Conductors (CC) by thermal co-evaporation. This is an attractive vacuum technique thanks to the simplicity, low cost and intrinsic uniformity over large areas. Recently, we published the in situ preparation route of 1 μm thick superconducting YBCO films deposited onto CeO2 buffered Ni biaxially textured tapes using a reel-to-reel system; end-to-end critical current densities Jc's at 77 K and self-field, measured by transport measurements are in the 1-2 MA/cm2 range for 1 m. long samples, with zero-resistance Tc= 87 K and transition widths DTc<3 K. In spite of the very good CC’s performances reported by a number of laboratories all over the world, several steps must be optimized in order to limit the CC production costs, in particular concerning the complexity of the CC architecture and the choice and optimization of the YBCO deposition technique. We specifically address the following critical points regarding: 1) the in situ oxidation of the YBCO layer using a novel supersonic nozzle, 2) the deposition by thermal or e-beam evaporation of thick crack-free CeO2 buffer layers and 3) the scaling-up of the deposition process using a new multichamber system.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Buffer layer architecture'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles