Journal articles: 'Piezoelectric Zinc Oxide Thin Films'

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Sidek, Fatini, Anis Nurashikin Nordin, and Raihan Othman. "Optimization of Zinc Oxide Thin Films for Silicon Surface Acoustic Wave Resonator Applications." Advanced Materials Research 518-523 (May 2012): 3772–79. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3772.

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High quality ZnO thin films are required to produce CMOS SAW resonators operating with low losses and high Q. This work intends to develop high performance CMOS SAW resonators through optimization of both the quality of the ZnO and the design of the SAW resonator. Zinc oxide was chosen for this work as the piezoelectric material due to its superior acoustic propagation properties and compatibility with integrated circuit fabrication techniques. ZnO has demonstrated good performance characteristics for a variety of piezoelectric devices. For optimization of the quality of the deposited ZnO thin film, different RF-sputtering conditions will be used to investigate which condition produces the best piezoelectric quality of the ZnO thin film. The experiments were carried using Taguchi optimization method, which studies a large number of variables with a small number of experiments.

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Kräuter, Marianne, Taher Abu Ali, Barbara Stadlober, Roland Resel, Katrin Unger, and Anna Maria Coclite. "Tuning the Porosity of Piezoelectric Zinc Oxide Thin Films Obtained from Molecular Layer-Deposited “Zincones”." Materials 15, no. 19 (September 30, 2022): 6786. http://dx.doi.org/10.3390/ma15196786.

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Porous zinc oxide (ZnO) thin films were synthesized via the calcination of molecular layer-deposited (MLD) “zincone” layers. The effect of the MLD process temperature (110 °C, 125 °C) and of the calcination temperature (340 °C, 400 °C, 500 °C) on the chemical, morphological, and crystallographic properties of the resulting ZnO was thoroughly investigated. Spectroscopic ellipsometry reveals that the thickness of the calcinated layers depends on the MLD temperature, resulting in 38–43% and 52–56% of remaining thickness for the 110 °C and 125 °C samples, respectively. Ellipsometric porosimetry shows that the open porosity of the ZnO thin films depends on the calcination temperature as well as on the MLD process temperature. The maximum open porosity of ZnO derived from zincone deposited at 110 °C ranges from 14.5% to 24%, rising with increasing calcination temperature. Compared with the 110 °C samples, the ZnO obtained from 125 °C zincone yields a higher porosity for low calcination temperatures, namely 18% for calcination at 340 °C; and up to 24% for calcination at 500 °C. Additionally, the porous ZnO thin films were subjected to piezoelectric measurements. The piezoelectric coefficient, d33, was determined to be 2.8 pC/N, demonstrating the potential of the porous ZnO as an, e.g., piezoelectric sensor or energy harvester.

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Abinaya, M., K. M. Dhanisha, M. Manoj Cristopher, P. Deepak Raj, K. Jeyadheepan, and M. Sridharan. "Reactive DC Magnetron Sputtered ZnO Thin Films for Piezoelectric Application." International Journal of Nanoscience 17, no. 03 (May 21, 2018): 1760047. http://dx.doi.org/10.1142/s0219581x1760047x.

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Zinc oxide (ZnO) films have been sputter coated over glass substrates at different cathode powers. Influence of cathode power on physical characteristics of ZnO samples was analyzed using X-ray diffractometer (XRD), field emission-scanning electron microscopy (FE-SEM), UV-Visible spectrophotometer and four-point probe (FPP) method. XRD patterns exhibited [Formula: see text]-axis-oriented ZnO and enhanced crystallinity with increase in cathode power due to the increase in adatom mobility. Uniformly arranged spherical grains were observed from FE-SEM images. The grain size increased from 25 to 40[Formula: see text]nm with increase in power. All samples exhibited high electrical resistance (G[Formula: see text]) which is compatible for piezoelectric application.

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Saito, Eduardo, E. F. Antunes, Matheus Pianassola, Fernando Henrique Christovan, João Paulo Barros Machado, Evaldo Jose Corat, and Vladimir J. Trava-Airoldi. "Electrodeposition of Zinc Oxide on Graphene Tips Electrochemically Exfoliated and O₂-Plasma Treated." Advanced Materials Research 975 (July 2014): 179–83. http://dx.doi.org/10.4028/www.scientific.net/amr.975.179.

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Zinc oxide (ZnO) presents several applications as piezoelectric transducers, photosensors, solar cells, electrochemical sensors, etc. Electrodeposition of zinc oxide (ZnO) thin films from aqueous solution of zinc nitrate has been deposited in graphenated low cost pencil graphite. The electrochemical graphene production at the tips was performed in a low cost DC source using concentrated sulfonitric solution. The tips were expanded in hydrogen plasma and treated by oxygen plasma to enhance its hydrophilicity. The posterior ZnO electrodeposition was highly efficient and the graphene functionalization contributes to overall electrochemical deposition mechanism.

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Sharma, Pallavi, Zeynel Guler, and Nathan Jackson. "Development and characterization of confocal sputtered piezoelectric zinc oxide thin film." Vacuum 184 (February 2021): 109930. http://dx.doi.org/10.1016/j.vacuum.2020.109930.

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Laurenti, M., S. Stassi, M. Lorenzoni, M. Fontana, G. Canavese, V. Cauda, and C. F. Pirri. "Evaluation of the piezoelectric properties and voltage generation of flexible zinc oxide thin films." Nanotechnology 26, no. 21 (May 6, 2015): 215704. http://dx.doi.org/10.1088/0957-4484/26/21/215704.

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Abu Ali, Taher, Julian Pilz, Philipp Schäffner, Markus Kratzer, Christian Teichert, Barbara Stadlober, and Anna Maria Coclite. "Piezoelectric Properties of Zinc Oxide Thin Films Grown by Plasma‐Enhanced Atomic Layer Deposition." physica status solidi (a) 217, no. 21 (September 22, 2020): 2000319. http://dx.doi.org/10.1002/pssa.202000319.

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Srivastava, Vinay Kumar, Jaspreet Singh, Parlad Kumar, Sataypal Singh Arora, Satinder Pal Singh, and Surinder Singh. "A comparative study of structural, mechanical & electrical properties of ZnO and AlN thin films for MEMS based piezoelectric sensors." Materials Research Express 9, no. 2 (February 1, 2022): 026402. http://dx.doi.org/10.1088/2053-1591/ac4341.

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Abstract In this work, a comparative study has been carried out to compare the relative performance of ZnO (Zinc Oxide) and AlN (Aluminum Nitride) thin films for their application in piezoelectric sensors. The thin films material properties are being characterized using various material characterization techniques such as SEM, XRD, and Nanoindentation. Further the MIM (Metal-Insulator-Metal) based devices have been fabricated with piezoelectric films sandwiched between Al electrodes. The devices have been evaluated for mechanical and electrical performances. The natural frequency of the devices recorded as 46.8 kHz (ZnO) and 40.8 kHz (AlN). The average nominal capacitance of the MIM structure is measured as ∼98 pF and ∼120 pF where as corresponding dissipation factor obtained as ∼0.03 and ∼0.0005 respectively for ZnO and AlN devices. The repeatability investigation carried out on the sample devices for up to 90 days and the output has been monitored. The result showed that the AlN devices exhibit better output stability compared to ZnO devices.

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Li, Wei, Yunqi Cao, and Nelson Sepúlveda. "Thin Film Piezoelectric Nanogenerator Based on (100)-Oriented Nanocrystalline AlN Grown by Pulsed Laser Deposition at Room Temperature." Micromachines 14, no. 1 (December 30, 2022): 99. http://dx.doi.org/10.3390/mi14010099.

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In wearable or implantable biomedical devices that typically rely on battery power for diagnostics or operation, the development of flexible piezoelectric nanogenerators (NGs) that enable mechanical-to-electrical energy harvesting is finding promising applications. Here, we present the construction of a flexible piezoelectric nanogenerator using a thin film of room temperature deposited nanocrystalline aluminium nitride (AlN). On a thin layer of aluminium (Al), the AlN thin film was grown using pulsed laser deposition (PLD). The room temperature grown AlN film was composed of crystalline columnar grains oriented in the (100)-direction, as revealed in images from transmission electron microscopy (TEM) and X-ray diffraction (XRD). Fundamental characterization of the AlN thin film by piezoresponse force microscopy (PFM) indicated that its electro-mechanical energy conversion metrics were comparable to those of c-axis oriented AlN and zinc oxide (ZnO) thin films. Additionally, the AlN-based flexible piezoelectric NG was encapsulated in polyimide to further strengthen its mechanical robustness and protect it from some corrosive chemicals.

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TAHIR, MUHAMMAD BILAL, HASNAIN JAVAD, KHALID NADEEM, and A. MAJID. "ZnO THIN FILMS: RECENT DEVELOPMENT, FUTURE PERSPECTIVES AND APPLICATIONS FOR DYE SENSITIZED SOLAR CELL." Surface Review and Letters 25, no. 07 (October 2018): 1930001. http://dx.doi.org/10.1142/s0218625x19300016.

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Dye sensitized solar cells (DSSCs) provide promisingly, organic–inorganic, clean hybrid, cost effective and efficient molecular solar cell devices. Due to their distinct and multifunctional qualities, zinc oxide (ZnO) nanostructures are promising materials used to create photoanodes for DSSCs due to the availability of larger surface area than bulk sheet substance, effectual light-dispersing centers, and when mixed with titanium dioxide they produce a core–shell formation that diminishes the coalition rate and provide direct charge. Moreover, ZnO thin sheets have been broadly observed due of its potential application in various fields i.e. piezoelectric, photovoltaic, pyroelectric and optoelectronic utilization. This review studies the recent advances in the fabrication of zinc oxide-based photovoltaics; synthesis of ZnO nanostructures with variable morphologies including thin sheets, nanotubes, nanorods, nanoflowers, nanofibers and factors that control the growth and morphologies of these nanospecies and part of crystallographic planes for the fabrication of various zinc oxide nanoshapes. In the next part of this paper, numerous fabrication routes — doped and undoped ZnO thin films — are discussed and different parameters of photovoltaics are investigated, e.g. efficiency pre and post annealing temperatures, fill factors spinning speed and coating time, additives, nature of precursor which impacts on morphological and optical parameters of these sheets. In short, this review is dedicated to the ZnO photoanode, its properties, issues related to ZnO photoanode, various improvement approaches, fabrication methods successfully trialled so far followed by market potential of the DSSC technology, conclusion and recommendations

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Zhang, Yuxia, Yanghui Jiang, Chi Ma, Jun Zhang, and Bing Yang. "Preparation of ZnO Piezoelectric Thin-Film Material for Ultrasonic Transducers Applied in Bolt Stress Measurement." Coatings 13, no. 9 (September 1, 2023): 1538. http://dx.doi.org/10.3390/coatings13091538.

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The measurement of bolt preload by using ultrasound can be accurate, convenient, and can realize the real-time monitoring of the change in the residual axial stress of a bolt during use. In order to realize the ultrasonic measurement of bolt preload, the use of zinc oxide (ZnO) piezoelectric thin-film material as an ultrasonic transducer material to stimulate an ultrasonic signal on the bolt is a feasible solution. In this paper, we choose to use RF magnetron sputtering technology to prepare ZnO piezoelectric thin-film materials and study the effects of sputtering power and target substrate distance on the structure and ultrasonic properties of ZnO piezoelectric thin films during the preparation process, in order to lay the foundation for realizing the application of ZnO piezoelectric thin films in the field of bolt preload measurement. The experimental results show that too-large sputtering power or too-small target substrate distance will result in the particles having too much kinetic energy during sputtering and exhibiting a structure of multiorientation growth, which excites ultrasonic longitudinal–transverse waves. A sputtering power of 600 W, sputtering time of 4 h, and target substrate distance of 100 mm are ideal experimental parameters for a ZnO piezoelectric thin-film material to be excited by an ultrasonic longitudinal wave signal, and its ideal operating frequency is 41 MHZ. These research results of bolt stress detection demonstrate good application prospects.

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Paraguay D., F., M. Miki-Yoshida, and F. Espinosa-Magaña. "EELS Studies of ZnO and ZnO:In Films Deposited By Spray Pyrolysis." Microscopy and Microanalysis 7, S2 (August 2001): 1224–25. http://dx.doi.org/10.1017/s1431927600032190.

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Zinc oxide based coatings are of much interest in science and technology due to their interesting applications, such as in gas sensor devices, transparent electrodes, piezoelectric devices, varistor ,surface acoustic-wave devices ,etc. Thin films of ZnO also have some advantages over indium tin oxide (ITO) and tin oxide, which are usually used as transparent conductors, the former are chemically stable to a hydrogen plasma such as that used in the elaboration of solar cells. Many techniques have been employed to produce zinc oxide based coatings e.g. radio frequency magnetron, spray pyrolysis, sputtering, chemical vapor deposition, sol gel, pulsed laser deposition, etc. Among these techniques, the spray pyrolysis has proved to be a simple, reproducible, and inexpensive method, particularly useful for large area applications.The main features of the spray pyrolytic system are fully described elsewhere. We have used a spray system attached onto mobile stage that provides a sweeping movement to the spray nozzle.

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Gartner, Mariuca, Hermine Stroescu, Daiana Mitrea, and Madalina Nicolescu. "Various Applications of ZnO Thin Films Obtained by Chemical Routes in the Last Decade." Molecules 28, no. 12 (June 9, 2023): 4674. http://dx.doi.org/10.3390/molecules28124674.

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This review addresses the importance of Zn for obtaining multifunctional materials with interesting properties by following certain preparation strategies: choosing the appropriate synthesis route, doping and co-doping of ZnO films to achieve conductive oxide materials with p- or n-type conductivity, and finally adding polymers in the oxide systems for piezoelectricity enhancement. We mainly followed the results of studies of the last ten years through chemical routes, especially by sol-gel and hydrothermal synthesis. Zinc is an essential element that has a special importance for developing multifunctional materials with various applications. ZnO can be used for the deposition of thin films or for obtaining mixed layers by combining ZnO with other oxides (ZnO-SnO2, ZnO-CuO). Also, composite films can be achieved by mixing ZnO with polymers. It can be doped with metals (Li, Na, Mg, Al) or non-metals (B, N, P). Zn is easily incorporated in a matrix and therefore it can be used as a dopant for other oxidic materials, such as: ITO, CuO, BiFeO3, and NiO. ZnO can be very useful as a seed layer, for good adherence of the main layer to the substrate, generating nucleation sites for nanowires growth. Thanks to its interesting properties, ZnO is a material with multiple applications in various fields: sensing technology, piezoelectric devices, transparent conductive oxides, solar cells, and photoluminescence applications. Its versatility is the main message of this review.

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Abdallah, Bassam, Walaa Zetoun, and Karam Masloub. "Study of Zinc Oxide Films Growth on Aluminum Nitride and Silicon Substrates: Structural, Optical and Electrical Properties." Solid State Phenomena 345 (July 28, 2023): 109–21. http://dx.doi.org/10.4028/p-eix5yn.

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ZnO films were deposited by magnetron sputtering using RF power supply, in order to study the effect of substrates on quality of the prepared films. Then, growth of the ZnO films on thin AlN buffer layer and Si(100) substrates were characterized using different techniques. The surface morphology was investigated by means of scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The structural properties were investigated via X-ray diffraction (XRD) patterns, Rocking Curve as well as Pole figures. The ZnO films were textured and they had preferred orientation (002) and the crystallinity was better for ZnO/Si in the used growth conditions. The XRD results were confirmed by HRTEM. Optical properties were analyzed by photoluminescence (PL), as well as electrical characteristics were performed by C-V and I-V measurements. The dispersion orientation of these films, as indicated via the FWHM (rocking curves), is small for thin ZnO/Si. These results are considered as hopeful for piezoelectric applications.

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Deschanvres, J. L., P. Rey, G. Delabouglise, M. Labeau, J. C. Joubert, and J. C. Peuzin. "Characterization of piezoelectric properties of zinc oxide thin films deposited on silicon for sensors applications." Sensors and Actuators A: Physical 33, no. 1-2 (May 1992): 43–45. http://dx.doi.org/10.1016/0924-4247(92)80223-p.

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Li, Yongkuan, Xinxing Liu, Dan Wen, Kai Lv, Gang Zhou, Yue Zhao, Congkang Xu, and Jiangyong Wang. "Growth of c-plane and m-plane aluminium-doped zinc oxide thin films: epitaxy on flexible substrates with cubic-structure seeds." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 76, no. 2 (March 19, 2020): 233–40. http://dx.doi.org/10.1107/s2052520620002668.

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Manufacturing high-quality zinc oxide (ZnO) devices demands control of the orientation of ZnO materials due to the spontaneous and piezoelectric polarity perpendicular to the c-plane. However, flexible electronic and optoelectronic devices are mostly built on polymers or glass substrates which lack suitable epitaxy seeds for the orientation control. Applying cubic-structure seeds, it was possible to fabricate polar c-plane and nonpolar m-plane aluminium-doped zinc oxide (AZO) films epitaxially on flexible Hastelloy substrates through minimizing the lattice mismatch. The growth is predicted of c-plane and m-plane AZO on cubic buffers with lattice parameters of 3.94–4.63 Å and 5.20–5.60 Å, respectively. The ∼80 nm-thick m-plane AZO film has a resistivity of ∼11.43 ± 0.01 × 10−4 Ω cm, while the c-plane AZO film shows a resistivity of ∼2.68 ± 0.02 × 10−4 Ω cm comparable to commercial indium tin oxide films. An abnormally higher carrier concentration in the c-plane than in the m-plane AZO film results from the electrical polarity along the c-axis. The resistivity of the c-plane AZO film drops to the order of 10−5 Ω cm at 500 K owing to the semiconducting behaviour. Epitaxial AZO films with low resistivities and controllable orientations on flexible substrates offer optimal transparent electrodes and epitaxy seeds for high-performance flexible ZnO devices.

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Sutjipto, Agus Geter Edy, Yit Pei Shian, Ali Shaitir, Mohamad Ashry Jusoh, and Ari Legowo. "Ambient Energy Harvesting of Piezoelectric ZnO Thin Film Dependence of Spin Speed and Annealing Temperature." Materials Science Forum 981 (March 2020): 51–58. http://dx.doi.org/10.4028/www.scientific.net/msf.981.51.

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This research deals with ambient energy harvesting by using zinc oxide thin film. The objectives of this thesis are to prove the ZnO film as a piezoelectric material can produce electric when vibration is applied and determine its optimal voltage. The thesis describes the sol gel spin coating technique to fabricate zinc oxide thin film. Zinc acetate dehydrate, absolute ethanol and diethanolamine were used in this thesis to act as sol gel precursor. Sol gel was coated on glass slide which wrapped by aluminum foil. The thin film was formed after preheating and annealing. The thin film was characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Photoluminescence spectroscopy (PL) and Ultraviolet-visible spectroscopy (UV-Vis) as well as analyzed using vibration technique. From XRD results, the films were preferentially diffracted at around 65° which corresponding to (1 1 2) diffraction phase. From FESEM results, it was observed that when the spin speed was increased at same annealing temperature, the thickness was also decreased. When the annealing temperature was increased at same spin speed, both grain size and thickness were increased. From the PL results, there was only film with spin speed of 2000 rpm and annealing temperature of 300 °C had slightly left wavelength which was 380 nm. Annealing temperature would affect only the intensity of PL wavelength. From the results of UV-Vis, it was observed that when the spin speed was increased at same annealing temperature, the band gap was decreased. When the annealing temperature was increased at same spin speed, the band gap was decreased. Piezoelectric test had proven the ZnO film could produce electricity. The maximum voltage (20.7 mV) was produced by the ZnO film with spin speed of 2000 rpm and annealing temperature of 300 °C.

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Amakali, Theopolina, Likius S. Daniel, Veikko Uahengo, Nelson Y. Dzade, and Nora H. de Leeuw. "Structural and Optical Properties of ZnO Thin Films Prepared by Molecular Precursor and Sol–Gel Methods." Crystals 10, no. 2 (February 22, 2020): 132. http://dx.doi.org/10.3390/cryst10020132.

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Zinc oxide (ZnO) is a versatile and inexpensive semiconductor with a wide direct band gap that has applicability in several scientific and technological fields. In this work, we report the synthesis of ZnO thin films via two simple and low-cost synthesis routes, i.e., the molecular precursor method (MPM) and the sol–gel method, which were deposited successfully on microscope glass substrates. The films were characterized for their structural and optical properties. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for piezoelectric applications. The surface roughness derived from atomic force microscopy (AFM) analysis indicates that films prepared via MPM were relatively rough with an average roughness (Ra) of 2.73 nm compared to those prepared via the sol–gel method (Ra = 1.55 nm). Thin films prepared via MPM were more transparent than those prepared via the sol–gel method. The optical band gap of ZnO thin films obtained via the sol–gel method was 3.25 eV, which falls within the range found by other authors. However, there was a broadening of the optical band gap (3.75 eV) in thin films derived from MPM.

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Kamardin, Ili Liyana Khairunnisa, and Ainun Rahmahwati Ainuddin. "Studies on Effect of Zinc Oxide (ZnO) Nanostructures Morphology by Modification of Sol-Gel Solution." Advanced Materials Research 1125 (October 2015): 106–10. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.106.

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Zinc Oxide (ZnO) known as wide band gap semiconductor with large excitation energy 60 meV, noncentral symmetry, piezoelectric and biocompatible for biomedical application are the unique characteristic that attract many researcher’s attention on ZnO nanostructure synthesis and physical properties. ZnO thin films were deposited on Si Glass substrate by a sol-gel process. The starting solution were prepare by dissolved zinc acetate dehydrate (ZnAc) and diethanolamine (DEA) in water (H2O) and 2-propanol (2-PrOH). 0 to 60 drops of NaOH were dropped into 100 ml sol-gel solution to study effect of sol-gel modification. ZnO thin films were obtained after preheating the spin coated thin films at 100 °C for 10 minutes after each coating. The coated substrates were undergone for Hot Water Treatment (HWT) process at 90 °C for 6 hours to grow ZnO nanostructures. The effects of sol-gel modification by drop of NaOH into the solution were studied. ZnO nanorods and nanoflakes were obtained after hot water treated at 90 °C for 6 hours with different amount of NaOH dropped directly in the sol-gel solution. On the basis of the changes in morphology and microstructure induced by hot water treatment, it is concluded that the amount of NaOH dropped into sol-gel effected morphology of ZnO growth.

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Li, Yongkuan, Jincong Feng, Jintong Zhang, Baitong He, Yue Wu, Yue Zhao, Congkang Xu, and Jiangyong Wang. "Towards high-performance linear piezoelectrics: Enhancing the piezoelectric response of zinc oxide thin films through epitaxial growth on flexible substrates." Applied Surface Science 556 (August 2021): 149798. http://dx.doi.org/10.1016/j.apsusc.2021.149798.

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Jeronimo, Karina, Vasileios Koutsos, Rebecca Cheung, and Enrico Mastropaolo. "PDMS-ZnO Piezoelectric Nanocomposites for Pressure Sensors." Sensors 21, no. 17 (August 31, 2021): 5873. http://dx.doi.org/10.3390/s21175873.

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The addition of piezoelectric zinc oxide (ZnO) fillers into a flexible polymer matrix has emerged as potential piezocomposite materials that can be used for applications such as energy harvesters and pressure sensors. A simple approach for the fabrication of PDMS-ZnO piezoelectric nanocomposites based on two ZnO fillers: nanoparticles (NP) and nanoflowers (NF) is presented in this paper. The effect of the ZnO fillers’ geometry and size on the thermal, mechanical and piezoelectric properties is discussed. The sensors were fabricated in a sandwich-like structure using aluminium (Al) thin films as top and bottom electrodes. Piezocomposites at a concentration of 10% w/w showed good flexibility, generating a piezoelectric response under compression force. The NF piezocomposites showed the highest piezoelectric response compared to the NP piezocomposites due to their geometric connectivity. The piezoelectric compound NF generated 4.2 V while the NP generated 1.86 V under around 36 kPa pressure. The data also show that the generated voltage increases with increasing applied force regardless of the type of filler.

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Mariotti, Giulia, and Lorenzo Vannozzi. "Fabrication, Characterization, and Properties of Poly (Ethylene-Co-Vinyl Acetate) Composite Thin Films Doped with Piezoelectric Nanofillers." Nanomaterials 9, no. 8 (August 20, 2019): 1182. http://dx.doi.org/10.3390/nano9081182.

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Ethylene vinyl acetate (EVA) is a copolymer comprehending the semi-crystalline polyethylene and amorphous vinyl acetate phases, which potentially allow the fabrication of tunable materials. This paper aims at describing the fabrication and characterization of nanocomposite thin films made of polyethylene vinyl acetate, at different polymer concentration and vinyl acetate content, doped with piezoelectric nanomaterials, namely zinc oxide and barium titanate. These membranes are prepared by solvent casting, achieving a thickness in the order of 100–200 µm. The nanocomposites are characterized in terms of morphological, mechanical, and chemical properties. Analysis of the nanocomposites shows the nanofillers to be homogeneously dispersed in EVA matrix at different vinyl acetate content. Their influence is also noted in the mechanical behavior of thin films, which elastic modulus ranged from about 2 to 25 MPa, while keeping an elongation break from 600% to 1500% and tensile strength from 2 up to 13 MPa. At the same time, doped nanocomposite materials increase their crystallinity degree than the bare ones. The radiopacity provided by the addition of the dopant agents is proven. Finally, the direct piezoelectricity of nanocomposites membranes is demonstrated, showing higher voltage outputs (up to 2.5 V) for stiffer doped matrices. These results show the potentialities provided by the addition of piezoelectric nanomaterials towards mechanical reinforcement of EVA-based matrices while introducing radiopaque properties and responsiveness to mechanical stimuli.

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Chang, Yu-Chen, Ying-Chung Chen, Bing-Rui Li, Wei-Che Shih, Jyun-Min Lin, Wei-Tsai Chang, and Chien-Chuan Cheng. "Effects of Thermal Annealing on the Characteristics of High Frequency FBAR Devices." Coatings 11, no. 4 (March 30, 2021): 397. http://dx.doi.org/10.3390/coatings11040397.

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In this study, piezoelectric zinc oxide (ZnO) thin film was deposited on the Pt/Ti/SiNx/Si substrate to construct the FBAR device. The Pt/Ti multilayers were deposited on SiNx/Si as the bottom electrode and the Al thin film was deposited on the ZnO piezoelectric layer as the top electrode by a DC sputtering system. The ZnO thin film was deposited onto the Pt thin film by a radio frequency (RF) magnetron sputtering system. The cavity on back side for acoustic reflection of the FBAR device was achieved by KOH solution and reactive ion etching (RIE) processes. The crystalline structures and surface morphologies of the films were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The optimized as-deposited ZnO thin films with preferred (002)-orientation were obtained under the sputtering power of 80 W and sputtering pressure of 20 mTorr. The crystalline characteristics of ZnO thin films and the frequency responses of the FBAR devices can be improved by using the rapid thermal annealing (RTA) process. The optimized annealing temperature and annealing time are 400 °C and 10 min, respectively. Finally, the FBAR devices with structure of Al/ZnO/Pt/Ti/SiNx/Si were fabricated. The frequency responses showed that the return loss of the FBAR device with RTA annealing was improved from −24.07 to −34.66 dB, and the electromechanical coupling coefficient (kt2) was improved from 1.73% to 3.02% with the resonance frequency of around 3.4 GHz.

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Rathod, Somsing, Atul Vir Singh, Sudhir Chandra, and Shiban K. Koul. "Design, Fabrication and Characterization of ZnO Based Thin Film Bulk Acoustic Resonators." Advanced Materials Research 254 (May 2011): 144–47. http://dx.doi.org/10.4028/www.scientific.net/amr.254.144.

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In the present work we report design, simulation, fabrication and characterization of thin film bulk acoustic resonator (FBAR). The FBAR has been modeled as a single port device with two terminals. The FBAR has been fabricated using Si-SiO2-Al–ZnO-Al structure. Zinc Oxide (ZnO) films were deposited by RF magnetron sputtering using Ceramic ZnO target in Ar-O2(1:1) ambient without external substrate heating. The XRD result confirms the preferred C-axis orientation of the films required for good piezoelectric properties. These ZnO films have been used to fabricate air gap type resonator. A four mask process sequence was used for this purpose. Lift-off process was used to pattern Al top electrode. In order to create the air cavity under the active device area, the bulk Si was etched in 40 % KOH at 80 °C. A specially designed mechanical jig was used to protect the front side of the device during anisotropic etching. Vector network analyzer was used to measure the reflection coefficient (S11: Return Loss) of the device. The resonant frequency of the resonator was measured to be 2.89 GHz as compare to the simulated frequency of 2.85 GHz with a return loss of 14.51 dB.

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Cheng, Chien Chuan, Re Ching Lin, Wei Tsai Chang, Ying Chung Chen, Kuo Sheng Kao, and Sin Liang Ou. "Shear Mode ZnO Thin Film Applied in FBAR Sensor." Advanced Materials Research 201-203 (February 2011): 718–21. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.718.

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In this study, platinum (Pt) and zinc oxide (ZnO) had been adopted as electrode and piezoelectric layer of an FBAR sensor. Based on the off-axis deposition of the ZnO film, longitude and shear modes resonance phenomenon can be approached to sensitive in air and liquid respectively. The preferred orientation and crystal properties of the ZnO film were evaluated by X-ray diffraction (XRD) using a SHIMADZU XRD-6000 with Cu Kαradiation. The crosssections of the grain structures of ZnO films were observed by scanning electron microscopy (SEM) (Philips XL40 FESEM). The electrical resistance of the bottom electrode was measured using the van der Pauw four-point probe method. The HP8720 network analyzer and CASCADE probe station (RHM-06/V + GSG 150) were used to measure the frequency responses of FBAR devices. The result of FBAR frequency response in liquid, the quality factor of longitude mode is decayed apparent and shear mode is kept high value. The Pt electrode of FBAR sensor has to withstand attack of acid/alkali solution.

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Chandra, Sudhir, and Atul Vir Singh. "Preparation and Characterization of Piezoelectric Films of ZnO and AlN by RF Sputtering for RF MEMS Applications." Key Engineering Materials 500 (January 2012): 84–89. http://dx.doi.org/10.4028/www.scientific.net/kem.500.84.

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In present work, we report preparation and characterization of piezoelectric films of zinc oxide (ZnO) and aluminum nitride (AlN) by RF magnetron sputtering using respective ceramic targets. The effect of ambient gas, substrate temperature, RF power and sputtering pressure has been studied to get highly c-axis oriented films for potential applications in micro-electromechanical systems. The films were characterized by X-ray diffraction technique to identify the crystallographic orientation. It was observed that the film deposited in pure Argon (Ar) ambient were amorphous or weekly crystallized with no preferred (002) orientation. On the other hand, the films prepared in Ar-O2 for ZnO were highly c-axis oriented. Similarly AlN films were observed to be oriented along c-axis perpendicular to substrate only when deposited in mixture of Ar-N2. To demonstrate the application of piezoelectric properties, an FBAR device (Film Bulk Acoustic Resonator) using ZnO thin film was fabricated. ZnO films are very sensitive to the chemicals used in the micro-electro-mechanical systems (MEMS) fabrication processes which include acids, bases and etchants of different material layers (e.g. SiO2, chromium, gold etc.). A specially designed mechanical jig was used for physically protecting the film during Si anisotropic etching process in potassium hydroxide solution. The potential applications of these films in various RF MEMS devices have been discussed.

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Yuan, Yan Hui, He Jun Du, Xin Xia, and Yoke Rung Wong. "Modeling, Fabrication and Characterization of Piezoelectric ZnO-Based Micro-Sensors and Micro-Actuators." Applied Mechanics and Materials 444-445 (October 2013): 1636–43. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1636.

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In this study, capabilities of zinc oxide (ZnO) thin films in sensing and actuating were investigated using micromachined micro-cantilevers. A heterogeneous piezoelectric cantilever was modeled to study its response under voltage and/or external mechanical loading. A ZnO thin-film micro-cantilever was designed based on the developed theoretical model. Simulated tip deflections of the micro-cantilever were on the nanometer level under typical electrical and mechanical input. A prototype was fabricated with microfabrication techniques. The ZnO thin film was sputtered at room temperature and demonstrated good compatibility with common chemicals and processes in micromachining. The fabricated micro-cantilever was experimentally characterized for its actuating and sensing performance. For actuator characterization tip deflection of the micro-cantilever was detected by a laser Doppler vibrometer, while for sensor characterization the micro-cantilever was calibrated as an acceleration sensor using a reference accelerometer. The experimental resonant frequency, actuating and sensing sensitivities agreed well the design specifications.

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Hantova, Kamila, and Jiri Houska. "Molecular dynamics study of the growth of ZnO_x films." Journal of Applied Physics 132, no. 18 (November 14, 2022): 185304. http://dx.doi.org/10.1063/5.0106856.

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Crystalline zinc oxide thin films are important due to a combination of optical transparency, electrical conductivity, and piezoelectric and pyroelectric properties. These functional properties are improved with increasing perfection of the crystalline structure. In this paper, classical molecular dynamics with a reactive force field was used to simulate the atom-by-atom growth of ZnO x films on a crystalline template. Contrary to previous modeling studies, the effect of a wide range of process parameters (elemental ratio x, kinetic energy of arriving atoms, and fraction of fast atoms in the particle flux) on the film crystallinity was investigated. All the parameters were found to have a significant impact. Counterintuitively, the highest crystal quality was obtained for slightly overstoichiometric films with x > 1. The results provide a quantitative insight into the role of individual deposition parameters, and the identification of their optimum values facilitates a further improvement of the film properties.

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Islam, Md Jahirul, Hyeji Lee, Kihak Lee, Chanseob Cho, and Bonghwan Kim. "Piezoelectric Nanogenerators Fabricated Using Spin Coating of Poly(vinylidene fluoride) and ZnO Composite." Nanomaterials 13, no. 7 (April 6, 2023): 1289. http://dx.doi.org/10.3390/nano13071289.

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In this context, the open-circuit voltage generated by either poly (vinylidene fluoride) or PVDF and ZnO composite sample before being enhanced to 4.2 V compared to 1.2 V for the samples of pure PVDF. The spin coating method was used to create a composite film, which served as a piezoelectric nanogenerator (PNG). Zinc oxide (ZnO) nanoparticles and PVDF serve as the matrix for the coating structure. Thin films were created that employed the spin coating method to achieve the desired results of ZnO’s non-brittle outcome and piezoelectric characteristics, as well as PVDF for use in self-powered devices. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and fourier transform infrared (FT-IR) were used to evaluate the properties of these formations. The electrical properties of the film were measured using an oscilloscope. Results indicated that by adding ZnO nanoparticles to the PVDF samples, piezoelectric capabilities were enhanced compared to samples containing PVDF only. These results point to promising uses for various wearable devices, such as water strider robot systems and self-operating equipment.

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Garcia, Andrés Jenaro Lopez, Giuliano Sico, Maria Montanino, Viktor Defoor, Manojit Pusty, Xavier Mescot, Fausta Loffredo, Fulvia Villani, Giuseppe Nenna, and Gustavo Ardila. "Low-Temperature Growth of ZnO Nanowires from Gravure-Printed ZnO Nanoparticle Seed Layers for Flexible Piezoelectric Devices." Nanomaterials 11, no. 6 (May 28, 2021): 1430. http://dx.doi.org/10.3390/nano11061430.

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Zinc oxide (ZnO) nanowires (NWs) are excellent candidates for the fabrication of energy harvesters, mechanical sensors, and piezotronic and piezophototronic devices. In order to integrate ZnO NWs into flexible devices, low-temperature fabrication methods are required that do not damage the plastic substrate. To date, the deposition of patterned ceramic thin films on flexible substrates is a difficult task to perform under vacuum-free conditions. Printing methods to deposit functional thin films offer many advantages, such as a low cost, low temperature, high throughput, and patterning at the same stage of deposition. Among printing techniques, gravure-based techniques are among the most attractive due to their ability to produce high quality results at high speeds and perform deposition over a large area. In this paper, we explore gravure printing as a cost-effective high-quality method to deposit thin ZnO seed layers on flexible polymer substrates. For the first time, we show that by following a chemical bath deposition (CBD) process, ZnO nanowires may be grown over gravure-printed ZnO nanoparticle seed layers. Piezo-response force microscopy (PFM) reveals the presence of a homogeneous distribution of Zn-polar domains in the NWs, and, by use of the data, the piezoelectric coefficient is estimated to be close to 4 pm/V. The overall results demonstrate that gravure printing is an appropriate method to deposit seed layers at a low temperature and to undertake the direct fabrication of flexible piezoelectric transducers that are based on ZnO nanowires. This work opens the possibility of manufacturing completely vacuum-free solution-based flexible piezoelectric devices.

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Prokhorov, Evgen, Gabriel Luna-Bárcenas, José Martín Yáñez Limón, Alejandro Gómez Sánchez, and Yuriy Kovalenko. "Chitosan-ZnO Nanocomposites Assessed by Dielectric, Mechanical, and Piezoelectric Properties." Polymers 12, no. 9 (September 1, 2020): 1991. http://dx.doi.org/10.3390/polym12091991.

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The aim of this work is to structurally characterize chitosan-zinc oxide nanoparticles (CS-ZnO NPs) films in a wide range of NPs concentration (0–20 wt.%). Dielectric, conductivity, mechanical, and piezoelectric properties are assessed by using thermogravimetry, FTIR, XRD, mechanical, and dielectric spectroscopy measurements. These analyses reveal that the dielectric constant, Young’s modulus, and piezoelectric constant (d33) exhibit a strong dependence on nanoparticle concentration such that maximum values of referred properties are obtained at 15 wt.% of ZnO NPs. The piezoelectric coefficient d33 in CS-ZnO nanocomposite films with 15 wt.% of NPs (d33 = 65.9 pC/N) is higher than most of polymer-ZnO nanocomposites because of the synergistic effect of piezoelectricity of NPs, elastic properties of CS, and optimum NPs concentration. A three-phase model is used to include the chitosan matrix, ZnO NPs, and interfacial layer with dielectric constant higher than that of neat chitosan and ZnO. This layer between nanoparticles and matrix is due to strong interactions between chitosan’s side groups with ZnO NPs. The understanding of nanoscale properties of CS-ZnO nanocomposites is important in the development of biocompatible sensors, actuators, nanogenerators for flexible electronics and biomedical applications.

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Kim, Yun Hae, Jin Woo Lee, Riichi Murakami, Dong Myung Lee, Jin Cheol Ha, and Pang Pang Wang. "Effect of Atmosphere Temperature on Physical Properties of ZnO/Ag/ZnO on PET Films." Advanced Materials Research 988 (July 2014): 125–29. http://dx.doi.org/10.4028/www.scientific.net/amr.988.125.

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Transparent conductive layers on flexible substrates are important components of today’s optoelectronic technology. They are used in filters for plasma displays, low-e windows, solar cells, etc. At present, in-doped indium oxide (ITO) layers on PET substrate is the predominant transparent conducting oxide film in diverse practical applications. However, ITO is a relatively expensive material because indium is not abundant, but aluminum-doped zinc oxide (AZO) film is emerging as an alternative potential candidate to ITO thin film due to its abundance as a raw material, nontoxic nature, cost-effectiveness, easy fabrication, and good stability in plasma. They have, however, several drawbacks: they exhibit relatively high electrical resistance (sheet resistance, 20-200Ω), considerable emissivity, and significant absorption in the spectral region 1-2μm, in which transition from high transmittance to high reflectance takes place. Furthermore, these films do not block solar thermal radiation (0.7-3μm), which may cause overheating problems to devices such as electro-chromic and photovoltaic devices. On the other hand, ITO/Ag/ITO multilayer films are used to achieve high transparent conducting properties. A thin silver layer of about 10nm thickness is embedded between two ITO layers. The ITO/Ag/ITO film has very low sheet resistance, high optical transparency in the visible range, relatively lower thickness than single-layered ITO film, and better durability than single-layered silver film. In terms of ZnO, which is a wide direct band-gap semiconductor, ZnO has a band-gap energy of 3.37 eV with a binding energy as high as 60 meV at room temperature. ZnO has been applied to various domains for excellent physical and chemical properties, such as piezoelectric sensors, rheostats , gas sensors, semiconductor lasers, and transparent conductive films.

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Vladut, Cristina Maria, Susana Mihaiu, Ecaterina Tenea, Silviu Preda, Jose M. Calderon-Moreno, Mihai Anastasescu, Hermine Stroescu, et al. "Optical and Piezoelectric Properties of Mn-Doped ZnO Films Deposited by Sol-Gel and Hydrothermal Methods." Journal of Nanomaterials 2019 (February 10, 2019): 1–12. http://dx.doi.org/10.1155/2019/6269145.

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Nowadays, multifunctional materials are of high interest due to their ability to be used in different applications by controlling one or two parameters (e.g., morphology and/or dopant). Zinc oxide is an intensive-studied material because of its large usability. Recently, we have shown that the conduction, transparency, and charge carrier concentration of ZnO can be controlled by changing the dopants, leading to promising materials as transparent conductive oxide films. In this work, sol-gel (SG) and hydrothermal (HT) methods were used separately or in combination in order to obtain ZnO films doped with Mn (1, 2, and 5%) for possible application in transparent optoelectronics or as piezoelectric materials. The manganese (Mn) dopant in the form of anhydrous manganese acetate was used to obtain Mn-doped ZnO films. ZnO hydrothermal (HT) growth was made on a previously ZnO seed layer, formed by sol-gel method. The Mn-doped ZnO films were deposited on microscope glass and on Pt/Ti/SiO2/Si substrates. A comparative characterization of the films for their structure, morphology, and optical and piezoelectric properties was achieved. SG films exhibit equiaxed nanoparticles, with diameters around 50 nm, while the films prepared by HT show a homogeneous morphology consisting of uniform 1D nanorods, sized about 30 nm diameter and 200–300 nm length. XRD diffractograms evidenced the presence of zincite phase (wurtzite structure hexagonally close packed), with an improvement in crystallinity of the HT films (compared with SG ones), which present a stronger tendency to be oriented along (002) plane (c-axis) at 2% at Mn. Spectroscopic ellipsometry shows that the films obtained by SG are much thinner than the ones obtained by HT and that the refractive index is increasing with the percent of dopant. The band gap energy was found to decrease with the Mn doping level from 3.28 eV (undoped ZnO) to 3.10 eV (ZnO doped with 5 at% Mn) for the samples deposited on Pt/Ti/SiO2/Si. The maximum transmission is found for the undoped ZnO film and decreases with Mn concentration but remains over 78% in the visible range. From the piezoelectric tests, it was found that the d33 coefficient is much larger for the HT samples in comparison with the SG samples, especially for 2 and 5 at% Mn. The optical and piezoelectric results could be of interest for applications in optoelectronic or piezoelectric devices.

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Gao, Wei, Yu Zhang, Binghe Ma, Jian Luo, and Jinjun Deng. "Fabrication and calibration of nanostructured vanadium-doped ZnO-based micromachined sensor with superior sensitive for underwater acoustic measurement." Journal of Micromechanics and Microengineering 32, no. 1 (December 6, 2021): 015005. http://dx.doi.org/10.1088/1361-6439/ac3b8c.

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Abstract A high-performance micromachined piezoelectric sensor based nanostructured vanadium-doped zinc oxide (ZnO) film with air-backing has been developed and characterized for underwater acoustic application. The sensing cell with a low foot-print of 2.0 mm × 2.0 mm is fabricated by Micro electro mechanical systems (MEMS) technology using a ZnO-on-silicon-on-insulator process platform. An optimal ratio of piezoelectric coefficient to the relative permittivity is obtained about 6.3 in the Zn0.98V0.02O sensing cell, improving by an order of magnitude compared with other notable piezoelectric films, plays a mainly dominant role in the enhanced piezoelectric response. Calibrations in the standard underwater instrument have demonstrated that the presented sensor could achieve an acoustic pressure sensitivity of −165 ± 2 dB (1 V μPa−1) over a bandwidth 10 Hz–10 kHz, outperforming the same kind of reported devices. The maximum non-linearity is no more than 0.3%, the sensitivity variation is no more than ±0.7 dB in the temperature range from 10 °C to 50 °C, indicating a better stability and higher reliability. The proposed sensor with a superior acoustic sensitivity gives a great application potential in underwater acoustic measurements.

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ZHANG, YUE, XUE-CHUAN ZHANG, and SHU-BING WANG. "PREPARATION OF 1-3 CONNECTIVITY COMPOSITE FILMS OF WELL-ALIGNED ZnO WHISKER ARRAYS WITH AN ORGANIC RESIN." International Journal of Modern Physics B 20, no. 25n27 (October 30, 2006): 3658–62. http://dx.doi.org/10.1142/s0217979206040155.

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Zinc oxide whisker arrays well-aligned along [0001] direction have been grown on the substrates of glass and single crystal silicon by atmospheric metal organic chemical vapor deposition method (MOCVD). The SEM observation indicated that the whiskers were quite uniform in length and diameter. The whisker arrays were very dense, and the gap among the whiskers was less than 1 μm. The array materials were proposed as the component to prepare 1-3 piezoelectric composite film in-situ. Epoxy resin was used as the matrix materials. The key points to prepare the composites are how to make the resin enter the array and control a suitable thickness of the resin films. Several approaches were studied. The results showed that the best was the vertical sucking method. The SEM observations indicated that the thickness was well controlled as almost same as the length of the whiskers, and the resin perfectly entered the array without pore. The 1-3 piezoelectric composite film has great potential applications in micro sensor and actuator arrays.

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Nikulina, A. V., and T. A. Kuchmenko. "Sorption properties of modifiers of piezoquartz resonators based on 3d-elements." Proceedings of the Voronezh State University of Engineering Technologies 81, no. 2 (November 1, 2019): 268–72. http://dx.doi.org/10.20914/2310-1202-2019-2-268-272.

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Transition metals are complexing substances, that is why being incorporated into the sensor modifiers, they can improve detection discrimination. The method of piezoelectric microweighting was used to study the sorption characteristics of the films based on partially soluble phosphates of 3d-elements (manganese (II), iron (II and III), nickel, copper, zinc, chromium) and coatings bearing partially soluble ferrous salts (hydrated oxide, fluoride, carbonate, sulfide, phosphate). The salts were created immediately prior to analysis, with bee glue as a filming agent. The method of immersion sensors in suspension of the filming agent and partially soluble salt, that was kept homogeneous by ultrasonic bath, was recognized the best way of film formation. Sorption characteristics of the composed coatings of piezoelectric resonator were estimated by the area under sorption kinetic curve and by peak value of sensor oscillation frequency drop during analysis of equilibrium gaseous form received over pure substances (water, phenol, isopropanol, isobutanol, acetous acid, chloroform, benzene, toluene, acetone, ethyl acetate, ammonia, diethyl amine, triethylamine, tert-butylamine, benzylamine). It was possible to determine the identifying variables Aij, minimax values of those allow to detect individual substances in the mixed vapour. Modifier application of piezoelectric resonators of phosphates of different 3d-elements is more efficient than use of different salts of one element. The shortcoming of the proposed modifiers is temporarily stable amine (ammonia) complexation. Those analytes desorption from the films proceeds slowly, it is determined by the bond strength of complexes and takes from 2 to 6 hours. However, array of seven sensors, modified by phosphates of transition metals of group IV, allows to detect oxygen- and nitrogen-based compounds vapours in the mixed vapour as well as to detect ammonia, diethyl amine and triethylamine individually.)

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Schaper, Nicholas, Dheyaa Alameri, Yoosuk Kim, Brian Thomas, Keith McCormack, Mathew Chan, Ralu Divan, David J. Gosztola, Yuzi Liu, and Irma Kuljanishvili. "Controlled Fabrication of Quality ZnO NWs/CNTs and ZnO NWs/Gr Heterostructures via Direct Two-Step CVD Method." Nanomaterials 11, no. 7 (July 15, 2021): 1836. http://dx.doi.org/10.3390/nano11071836.

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A novel and advanced approach of growing zinc oxide nanowires (ZnO NWs) directly on single-walled carbon nanotubes (SWCNTs) and graphene (Gr) surfaces has been demonstrated through the successful formation of 1D–1D and 1D–2D heterostructure interfaces. The direct two-step chemical vapor deposition (CVD) method was utilized to ensure high-quality materials’ synthesis and scalable production of different architectures. Iron-based universal compound molecular ink was used as a catalyst in both processes (a) to form a monolayer of horizontally defined networks of SWCNTs interfaced with vertically oriented ZnO NWs and (b) to grow densely packed ZnO NWs directly on a graphene surface. We show here that our universal compound molecular ink is efficient and selective in the direct synthesis of ZnO NWs/CNTs and ZnO NWs/Gr heterostructures. Heterostructures were also selectively patterned through different fabrication techniques and grown in predefined locations, demonstrating an ability to control materials’ placement and morphology. Several characterization tools were employed to interrogate the prepared heterostructures. ZnO NWs were shown to grow uniformly over the network of SWCNTs, and much denser packed vertically oriented ZnO NWs were produced on graphene thin films. Such heterostructures can be used widely in many potential applications, such as photocatalysts, supercapacitors, solar cells, piezoelectric or thermal actuators, as well as chemical or biological sensors.

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Caliendo, Cinzia, Massimiliano Benetti, Domenico Cannatà, Alessio Buzzin, Francesca Grossi, Enrico Verona, and Giampiero de Cesare. "UV Sensor Based on Surface Acoustic Waves in ZnO/Fused Silica." Sensors 23, no. 9 (April 22, 2023): 4197. http://dx.doi.org/10.3390/s23094197.

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Zinc oxide (ZnO) thin films have been grown by radio frequency sputtering technique on fused silica substrates. Optical and morphological characteristics of as-grown ZnO samples were measured by various techniques; an X-ray diffraction spectrum showed that the films exhibited hexagonal wurtzite structure and were c-axis-oriented normal to the substrate surface. Scanning electron microscopy images showed the dense columnar structure of the ZnO layers, and light absorption measurements allowed us to estimate the penetration depth of the optical radiation in the 200 to 480 nm wavelength range and the ZnO band-gap. ZnO layers were used as a basic material for surface acoustic wave (SAW) delay lines consisting of two Al interdigitated transducers (IDTs) photolithographically implemented on the surface of the piezoelectric layer. The Rayleigh wave propagation characteristics were tested in darkness and under incident UV light illumination from the top surface of the ZnO layer and from the fused silica/ZnO interface. The sensor response, i.e., the wave velocity shift due to the acoustoelectric interaction between the photogenerated charge carriers and the electric potential associated with the acoustic wave, was measured for different UV power densities. The reversibility and repeatability of the sensor responses were assessed. The time response of the UV sensor showed a rise time and a recovery time of about 10 and 13 s, respectively, and a sensitivity of about 318 and 341 ppm/(mW/cm2) for top and bottom illumination, respectively. The ZnO/fused silica-based SAW UV sensors can be interrogated across the fused silica substrate thanks to its optical transparency in the UV range. The backlighting interrogation can find applications in harsh environments, as it prevents the sensing photoconductive layer from aggressive environmental effects or from any damage caused by cleaning the surface from dust which could deteriorate the sensor’s performance. Moreover, since the SAW sensors, by their operating principle, are suitable for wireless reading via radio signals, the ZnO/fused-silica-based sensors have the potential to be the first choice for UV sensing in harsh environments.

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39

Li, Z. W., W. Gao, and Roger J. Reeves. "Zinc oxide films by thermal oxidation of zinc thin films." Surface and Coatings Technology 198, no. 1-3 (August 2005): 319–23. http://dx.doi.org/10.1016/j.surfcoat.2004.10.111.

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Serra-Torrent, Albert, Pattabiraman Deepak Raj, Llibertad Abad, Aitor Lopeandia-Fernandez, Javier Rodriguez-Viejo, and Madanagurusamy Sridharan. "Vanadium-doped zinc oxide films for piezoelectric application." Nanomaterials and Energy 4, no. 2 (December 2015): 109–17. http://dx.doi.org/10.1680/jnaen.15.00023.

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41

Serra-Torrent, Albert, M. Sridharan, Aitor Lopeandia-Fernandez, Javier Rodriguez-Viejo, P. Deepak Raj, and Llibertad Abad. "Vanadium-doped zinc oxide films for piezoelectric application." Nanomaterials and Energy 4, July–December (July 1, 2015): 1–24. http://dx.doi.org/10.1680/nme.15.00023.

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42

Gaspar, D., L. Pereira, K. Gehrke, B. Galler, E. Fortunato, and R. Martins. "High mobility hydrogenated zinc oxide thin films." Solar Energy Materials and Solar Cells 163 (April 2017): 255–62. http://dx.doi.org/10.1016/j.solmat.2017.01.030.

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43

Bouznit, Y., Y. Beggah, and F. Ynineb. "Sprayed lanthanum doped zinc oxide thin films." Applied Surface Science 258, no. 7 (January 2012): 2967–71. http://dx.doi.org/10.1016/j.apsusc.2011.11.019.

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44

Hsu, Yu-Hsiang, John Lin, and William C. Tang. "RF sputtered piezoelectric zinc oxide thin film for transducer applications." Journal of Materials Science: Materials in Electronics 19, no. 7 (October 16, 2007): 653–61. http://dx.doi.org/10.1007/s10854-007-9415-1.

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45

Alivov, Ya I., A. V. Chernykh, M. V. Chukichev, and R. Y. Korotkov. "Thin polycrystalline zinc oxide films obtained by oxidation of metallic zinc films." Thin Solid Films 473, no. 2 (February 2005): 241–46. http://dx.doi.org/10.1016/j.tsf.2004.07.068.

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46

Matsumoto, Kenji, Yutaka Adachi, Takeshi Ohgaki, Isao Sakaguchi, Tsubasa Nakagawa, Naoki Ohashi, and Hajime Haneda. "Zinc Self-Diffusion in Isotopic Heterostructured Zinc Oxide Thin Films." Key Engineering Materials 421-422 (December 2009): 193–96. http://dx.doi.org/10.4028/www.scientific.net/kem.421-422.193.

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Zinc isotopic heterostructured zinc oxide thin films of 64ZnO/68ZnO/64ZnO were synthesized using pulsed laser deposition. The pulsed laser was first irradiated onto a polycrystalline target of 64ZnO to deposit the 64ZnO layer, then onto the 68ZnO target to prepare the 68ZnO layer and finally, the 64ZnO target was used again. The 64ZnO/68ZnO/64ZnO layered thin film was thus obtained. The thin films were annealed at various diffusion annealing temperatures. Diffusion profiles of the zinc isotopes due to the annealing were evaluated using secondary ion mass spectrometry (SIMS). The diffusion coefficients were slightly higher near the interface between the thin film and the substrate (the inner region) compared to the near surface (the outer region).

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Liu, Huajun, Haijun Wu, Khuong Phuong Ong, Tiannan Yang, Ping Yang, Pranab Kumar Das, Xiao Chi, et al. "Giant piezoelectricity in oxide thin films with nanopillar structure." Science 369, no. 6501 (July 16, 2020): 292–97. http://dx.doi.org/10.1126/science.abb3209.

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High-performance piezoelectric materials are critical components for electromechanical sensors and actuators. For more than 60 years, the main strategy for obtaining large piezoelectric response has been to construct multiphase boundaries, where nanoscale domains with local structural and polar heterogeneity are formed, by tuning complex chemical compositions. We used a different strategy to emulate such local heterogeneity by forming nanopillar regions in perovskite oxide thin films. We obtained a giant effective piezoelectric coefficient d33,f* of ~1098 picometers per volt with a high Curie temperature of ~450°C. Our lead-free composition of sodium-deficient sodium niobate contains only three elements (Na, Nb, and O). The formation of local heterogeneity with nanopillars in the perovskite structure could be the basis for a general approach to designing and optimizing various functional materials.

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Elimat, Z. M. "Optical characterization of poly (ethylene oxide)/zinc oxide thin films." Radiation Effects and Defects in Solids 169, no. 8 (June 30, 2014): 686–95. http://dx.doi.org/10.1080/10420150.2014.931402.

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Ondo-Ndong, R., H. Essone-Obame, and N. Koumba. "Electrical Performance of Zinc Oxide Thin Films Transistors." Journal of Nano- and Electronic Physics 9, no. 6 (2017): 06002–1. http://dx.doi.org/10.21272/jnep.9(6).06002.

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Skvortsova, V., M. Zubkins, R. Kalendarev, H. Arslan, and J. Purans. "Optical properties of zinc-iridium oxide thin films." IOP Conference Series: Materials Science and Engineering 503 (March 25, 2019): 012016. http://dx.doi.org/10.1088/1757-899x/503/1/012016.

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Journal articles on the topic 'Piezoelectric Zinc Oxide Thin Films'

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