ZnO sheet array was fabricated by a simple electrodeposition method on the transparent ITO substrate at a temperature of about 60℃. The field emission properties of the ZnO sheet array were investigated. The fluctuat...ZnO sheet array was fabricated by a simple electrodeposition method on the transparent ITO substrate at a temperature of about 60℃. The field emission properties of the ZnO sheet array were investigated. The fluctuation of the field emission current is less than 5% over several hours. The Fowler Nordheim curves with a roughly linear characteristic were obtained by analysing the current density and the intensity of the electrical field. The results prove that such a simple electrochemical method can potentially meet the demands on the production of cold cathodes for field emission display.展开更多
The ultraviolet (UV) photoresponses of Wurtzite GaN, ZnO, and 6H-SiC-based Optical Field Effect Transistor (OPFET) detectors are estimated with an in-depth analysis of the same considering the generalized model and th...The ultraviolet (UV) photoresponses of Wurtzite GaN, ZnO, and 6H-SiC-based Optical Field Effect Transistor (OPFET) detectors are estimated with an in-depth analysis of the same considering the generalized model and the front-illuminated model for high resolution imaging and UV communication applications. The gate materials considered for the proposed study are gold (Au) and Indium-Tin-Oxide (ITO) for GaN, Au for SiC, and Au and silver dioxide (AgO2) for ZnO. The results indicate significant improvement in the Linear Dynamic Range (LDR) over the previously investigated GaN OPFET (buried-gate, front-illuminated and generalized) models with Au gate. The generalized model has superior dynamic range than the front-illuminated model. In terms of responsivity, all the models including buried-gate OPFET exhibit high and comparable photoresponses. Buried-gate devices on the whole, exhibit faster response than the surface gate models except in the AgO2-ZnO generalized OPFET model wherein the switching time is the lowest. The generalized model enables faster switching than the front-illuminated model. The switching times in all the cases are of the order of nanoseconds to picoseconds. The SiC generalized OPFET model shows the highest 3-dB bandwidths of 11.88 GHz, 36.2 GHz, and 364 GHz, and modest unity-gain cut-off frequencies of 4.62 GHz, 8.71 GHz, and 5.71 GHz at the optical power densities of 0.575 μW/cm2, 0.575 mW/cm2, and 0.575 W/cm2 respectively. These are in overall, the highest detection-cum-amplifi-cation bandwidths among all the investigated devices. The same device exhibits the highest LDR of 73.3 dB. The device performance is superior to most of the other existing detectors along with comparable LDR, thus, emerging as a high performance photodetector for imaging and communication applications. All the detectors show considerably high detectivities owing to the high responsivity values. The results have been analyzed by the photovoltaic and the photoconductive effects, and the series resistance effects and will aid in conducting further research. The results are in line with the experiments and the commercially available software simulations. The devices will greatly contribute towards single photon counting, high resolution imaging, and UV communication applications.展开更多
Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron ...Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （PL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.展开更多
基金Project supported by the Key Program of Chinese Academy of Sciences （Grant No KGCX2-SW-602-2）, the Special Foundation for State Major Basic Research Program of China （Grant No G2001CB3095）, and the National Natural Science Foundation of China （Grant Nos 90606009, 60276024 and 60236010）.
文摘ZnO sheet array was fabricated by a simple electrodeposition method on the transparent ITO substrate at a temperature of about 60℃. The field emission properties of the ZnO sheet array were investigated. The fluctuation of the field emission current is less than 5% over several hours. The Fowler Nordheim curves with a roughly linear characteristic were obtained by analysing the current density and the intensity of the electrical field. The results prove that such a simple electrochemical method can potentially meet the demands on the production of cold cathodes for field emission display.
文摘利用电化学沉积法制得纳米氧化锌薄膜,再用该材料修饰ITO电极,并将该修饰电极应用于亚硝酸盐的检测研究.研究结果表明,在恒定电流9×10^-8 A、修饰时沉积时间为25min时,该修饰电极对亚硝酸盐的催化氧化效果最好.其峰电流与亚硝酸盐浓度在3.33×10^-8 M至3.33×10^-6 M范围内有良好线性关系.检出限低至1.0×10^-7 M.利用该电极对0.1 M NaCl和0.01 M NaNO 2混合溶液进行了5次平行测定,相对标准偏差(RSD)为±10.2%,该修饰电极灵敏度高,重现性好.
文摘The ultraviolet (UV) photoresponses of Wurtzite GaN, ZnO, and 6H-SiC-based Optical Field Effect Transistor (OPFET) detectors are estimated with an in-depth analysis of the same considering the generalized model and the front-illuminated model for high resolution imaging and UV communication applications. The gate materials considered for the proposed study are gold (Au) and Indium-Tin-Oxide (ITO) for GaN, Au for SiC, and Au and silver dioxide (AgO2) for ZnO. The results indicate significant improvement in the Linear Dynamic Range (LDR) over the previously investigated GaN OPFET (buried-gate, front-illuminated and generalized) models with Au gate. The generalized model has superior dynamic range than the front-illuminated model. In terms of responsivity, all the models including buried-gate OPFET exhibit high and comparable photoresponses. Buried-gate devices on the whole, exhibit faster response than the surface gate models except in the AgO2-ZnO generalized OPFET model wherein the switching time is the lowest. The generalized model enables faster switching than the front-illuminated model. The switching times in all the cases are of the order of nanoseconds to picoseconds. The SiC generalized OPFET model shows the highest 3-dB bandwidths of 11.88 GHz, 36.2 GHz, and 364 GHz, and modest unity-gain cut-off frequencies of 4.62 GHz, 8.71 GHz, and 5.71 GHz at the optical power densities of 0.575 μW/cm2, 0.575 mW/cm2, and 0.575 W/cm2 respectively. These are in overall, the highest detection-cum-amplifi-cation bandwidths among all the investigated devices. The same device exhibits the highest LDR of 73.3 dB. The device performance is superior to most of the other existing detectors along with comparable LDR, thus, emerging as a high performance photodetector for imaging and communication applications. All the detectors show considerably high detectivities owing to the high responsivity values. The results have been analyzed by the photovoltaic and the photoconductive effects, and the series resistance effects and will aid in conducting further research. The results are in line with the experiments and the commercially available software simulations. The devices will greatly contribute towards single photon counting, high resolution imaging, and UV communication applications.
基金Department of Science and Technology (DST), Government of India was gratefully acknowledged for their financial support under the NATAG program monitored by Dr. G. Sundararajan
文摘Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （PL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.
