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Effect of post-annealing on microstructure and piezoelectric properties of ZnO thin film for triangular shaped vibration energy harvester
摘要： In this paper, a triangular shaped piezoelectric vibration energy harvester (TS-PVEH) with zinc oxide (ZnO) thin films as the piezoelectric layer is reported. The effect of post-annealing temperature on the microstructure and piezoelectric performance of ZnO thin film deposited by magnetron sputtering method is investigated firstly. The results show that the optimum post-annealing temperature of 150 °C was the most beneficial to improve the piezoelectric properties of ZnO thin films. Four prototypes of TS-PVEH with different structure parameters are fabricated and optimized. The simulation and experiment results indicate that the height and width of the triangular structure have a significant influence on the vibration mode and the output performance of TS-PVEHs. The optimization results indicate that the third prototype has the best output performance. Its open-circuit voltage and short-circuit current are 290mV and 1.25 μA, respectively, when the vibration acceleration is 5m/s2 and the frequency is 56Hz. Moreover, it has the highest load power density of 0.035μW/cm2 when the load is 0.1MΩ.
关键词： Triangular substrate,ZnO thin film,Structure optimization,Post-annealing temperature,Vibration energy harvester
更新于2025-09-23 15:23:52
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Tuning Material Properties of ZnO Thin Films for Advanced Sensor Applications
摘要： We report on the growth of ZnO thin films by plasma-enhanced atomic layer deposition as a function of substrate temperature. The method to ensure self-limiting growth with precise thickness control is discussed and the effect of temperature on the texture of the thin films is presented. Switching the texture from (100) to (002) by increasing the substrate temperature is a key property for functional devices. The ZnO thin films with tailored properties could find applications in a wide range of sensors and actuators.
关键词： atomic layer deposition,ZnO,thin film,semiconductor
更新于2025-09-23 15:23:52
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Effects of Withdrawal Speeds on Properties of ZnO Thin Films Prepared by Sol-Gel Immerse Technique
摘要： ZnO thin films have attractive applications in photoelectric device, due to their excellent chemical, electrical and optical properties. In this paper, ZnO thin films with good c-axis preferred orientation and high transmittance are prepared on glass sheets by sol-gel immerse technique. The effects of withdrawal speeds on the growth process of thin film crystal, film crystal orientation and the crystallinity, the optical performance were investigated by XRD, SEM and UV-Vis spectrophotometry. The results show that the thin films were composed of better hexagonal wurtzite crystals with the c-axis prepared orientation. The transmittance of prepared thin films is over 80% in the visible-near IR region from 600 nm - 800 nm. ZnO films have sharp and narrow diffraction peaks, which indicates that the materials exhibit high crystallinity. With the withdrawal speeds increasing, the grain size of ZnO thin films and the intensity for all diffraction peaks were increased gradually. The growth model is changed from the stratified structure into the island structure in the growth process. The transmittance of the thin films decrease in the visible wavelength region, with the withdrawal speeds increasing.
关键词： Withdrawal speeds,ZnO thin film,C-axis preferred orientation,Sol-gel technique
更新于2025-09-23 15:23:52
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The Implementation of Fundamental Digital Circuits With ITO-Stabilized ZnO TFTs for Transparent Electronics
摘要： In this paper, several fundamental pseudo-CMOS digital circuits with n-type indium tin oxide-stabilized ZnO thin-film transistors (TFTs) were implemented and investigated. The optical transmittance of circuits varied from 77% to 92% throughout the visible wavelength band. Electrically, the operation frequency of inverters, nor gates, nand gates, D latches, and D flip flops were all found to exceed 10 kHz with a supply voltage of 10 V. Besides, 13-stage ring oscillators could be operated at 42 kHz with a propagation delay time of 0.92 μs when the supply voltage was set as 20 V. Among the state-of-the-art transparent designs, these proposed circuits based on the ITO-stabilized ZnO TFTs exhibited high-speed performance, which were promising as building blocks for transparent electronics with moderate frequency requirements.
关键词： transparent electronics,Digital circuits,indium tin oxide-stabilized ZnO,thin-film transistors (TFTs),ring oscillator (RO)
更新于2025-09-23 15:22:29
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Effects of yttrium doping on the electrical performances and stability of ZnO thin-film transistors
摘要： In this paper, we have investigated the effects of yttrium (Y) doping on the electrical performance and stability of ZnO thin film transistors (TFTs). Here, Y-doped ZnO TFTs were fabricated by using radio frequency magnetron sputtering at 150 °C. As a result, the 1% Y-doped ZnO TFT exhibits a small threshold voltage shifts of 2.5 V under positive bias stress and ?2.8 V under negative bias stress as well as desirable device performance with field effect mobility of 9.8 cm2/V s, a subthreshold swing of 320 mV/decade and on/off current ratio of 107, respectively. Based on the XPS analysis and electrical characterizations, the improvement in stability and electrical properties of ZnO TFTs were attributed to the appropriate Y doping concentration, which not only could control the carrier concentration and broaden the band gap of ZnO film, but also suppress the oxygen vacancy defects and passivate the trap density at the SiO2/ZnO interfaces. Consequently, the high stability and excellent electrical performances of Y-doped ZnO TFTs show great potential for use in flat panel displays.
关键词： Doping,Zinc oxide (ZnO),Thin film transistors (TFTs),Bias stress stability
更新于2025-09-23 15:22:29
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An In-Depth Study on Electrical and Hydrogen Sensing Characteristics of ZnO Thin Film with Radio Frequency Sputtered Gold Schottky Contacts
摘要： Electrical and hydrogen sensing characteristics of radio frequency sputtered Au/ZnO thin film Schottky diodes on n-silicon substrate have been investigated over a wide temperature range. Current-voltage characterizations of the device in the temperature range of 25°C to 200°C confirm its excellent rectifying property with forward to reverse current ratio of 1610 at an external bias of 5 V. Ideality factor in the range of 4.12 to 2.98 is obtained for Au/ZnO Schottky diode in the aforementioned temperature range, at atmospheric conditions. On exposing diode to hydrogen, a reduction in ideality factor is observed which makes thermionic emission more prominent. The proposed device has proven to be hydrogen sensitive, on account of the lateral shift observed in I ? V characteristics at different hydrogen concentrations (50 ppm-1000 ppm). Maximum barrier height variation of 99 meV and sensitivity of 144% have been observed at 1000 ppm hydrogen at 200°C. A Detailed perusal of the steady-state reaction kinetics of the sensor using I ? V characteristics affirmed that the atomistic hydrogen adsorption at Au/ZnO interface is accountable for the barrier height modulation. The studied sensor depicts remarkable performance for high-temperature detection.
关键词： Hydrogen sensing,Zinc oxide (ZnO) thin film,Electrical characteristics,Schottky diode,Metal-semiconductor interface,Palladium catalyst
更新于2025-09-23 15:22:29
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Utilizing embedded ultra-small Pt nanoparticles as charge trapping layer in flashristor memory cells
摘要： In this study, a methodology for producing highly controlled and uniformly dispersed metal nanoparticles were developed by atomic layer deposition (ALD) technique. All-ALD grown thin film flash memory (TFFM) cells and their applications were demonstrated with ultra-small platinum nanoparticles (Pt-NPs) as charge trapping layer and control tunnel oxide layer. The ultra-small Pt-NPs possessed sizes ranging from 2.3 to 2.6 nm and particle densities of about 2.5 × 1013 cm–b. The effect of Pt-NPs embedded on the storage layer for charging was investigated. The charging effect of ultra-small Pt-NPs the storage layer was observed using the electrical characteristics of TFFM. The Pt-NPs were observed by a high-resolution scanning electron microscopy (HR-SEM). The memory effect was manifested by hysteresis in the IDS-VDS and IDS-VGS curves. The charge storage capacity of the TFFM cells demonstrated that ALD-grown Pt-NPs in conjunction with ZnO layer can be considered as a promising candidate for memory devices. Moreover, ZnO TFFM showed a ION/IOFF ratio of up to 52 orders of magnitude ?a/b – Vgs curve. Fabricated TFFMs exhibited clear pinch-off and show n-type field effect transistor (FET) behavior. The role of atomic-scale controlled Pt-NPs for improvement of devices were also discussed and they indicated that ALD-grown Pt-NPs can be utilized in nanoscale electronic devices as alternative quantum dot structures.
关键词： ZnO,Thin film flash memory,Pt nanoparticle,Atomic layer deposition,Memristor
更新于2025-09-23 15:21:21
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Preparation of ZnO-carbon quantum dot composite thin films with superhydrophilic surface
摘要： Carbon quantum dots (CQDs)-ZnO composite thin films were prepared via ultrasonic mist vapour deposition (UMVD) method. The effect of different CQDs concentrations (C), substrate temperatures (Ts), nozzle-substrate distances and also post-annealing process on the thin film structure were considered and examined systematically. The effects of these parameters on optical, morphological and surface properties of the layers as well as their wettability were carefully investigated and discussed. It was found that for low Ts and short ‘d’, CQDs diffuse inside the layer during deposition and then were evaporated after annealing process making drastic changes in layer morphology and optical transmittance. On the other hand, for high Ts and long ‘d’, most of CQDs inside mist vapour drops are evaporated during deposition process. Therefore, the layer transmittance and morphology did not change notably after annealing. Interestingly, the layer prepared with C = 5 volume %, Ts = 470 °C and d = 9 cm was turned to super-hydrophilic surface after annealing process with contact angle of , 3o. Such a super-hydrophilic CQDS-ZnO thin film is highly beneficial for a wide range of applications which high wettability is required.
关键词： mist vapour deposition,super-hydrophilic,ZnO thin film,Carbon quantum dots
更新于2025-09-23 15:21:01
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Pulsed laser deposition of a ZnO:Eu3+ thin film: study of the luminescence and surface state under electron beam irradiation
摘要： A highly c-axis orientated Eu3+ doped ZnO (ZnO:Eu3+) thin film was successfully deposited by pulsed laser deposition in an oxygen working atmosphere. The structure, morphology, chemical analysis and luminescence properties of the sample were investigated. The effect of electron beam irradiation on the surface state, chemical and luminescence properties of the sample were studied. Successful incorporation of Eu3+ ions in the ZnO matrix was confirmed by X-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) analysis. XPS measurements revealed traces of the divalent (Eu2+) on the film surface while the trivalent (Eu3+) oxidation state in the bulk of the film. XPS depth profile confirmed that the film contained excess oxygen throughout the film. The film exhibited exciton and defect emission of ZnO as well as 4f – 4f characteristic emission of Eu3+ ions superimposed on the defect emission when excited at 325 nm using a He-Cd laser. Whereas only 4f – 4f characteristic emission of Eu3+ ions was recorded when the film was excited at 464 nm and also when excited with the electron beam. XPS high resolution spectra of the O 1s peak confirmed the creation of new defects during electron beam irradiation. In general, ZnO:Eu3+ films show potential for applications as a source of red light in optoelectronic devices.
关键词： Degradation,PLD,ZnO thin film,Eu3+ ions,Cathodoluminescence,Red emission,Electron beam irradiation
更新于2025-09-19 17:13:59
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Thermal Treatments and Photoluminescence Properties of ZnO and ZnO:Yb Films Grown by Magnetron Sputtering
摘要： This work is on ZnO and ZnO:Yb (0.3 at%) films prepared on (100) Si substrates by magnetron sputtering and deals with their structural and photoluminescence evolutions upon annealing at different temperatures from 873 to 1173 K during 1 h under N2 atmosphere. The microstructural characterizations reveal that, for both sample series, annealing treatment improves the crystallinity of ZnO of the upper part of the films. However, (002) textured ZnO columnar growth is only observed for ZnO films. For annealing temperatures higher than 973 K, rare earth and Si diffusions toward the film/substrate interface are observed resulting in the appearance of a zinc silicate phase for ZnO films and a composite material made of nanoscale ZnO grains surrounded by an amorphous phase for ZnO:Yb films. In addition, photoluminescence measurements show that Yb doping in ZnO results in a lower integrated photoluminescence intensity compared to that of ZnO films and the photoluminescence response in the visible spectral range is also modified most probably due to the presence of dopant. Furthermore, the PL intensity at 980 nm originating from electronic transitions between 2F5/2 and 2F7/2 levels of Yb3+ ion increased with temperature. At last, the evolutions of the PL emissions with temperature from the ZnO defects are discussed.
关键词： ZnO,thin film,magnetron sputtering,Yb doping
更新于2025-09-09 09:28:46