利用水热法生长的N型优质ZnO晶体材料蒸镀了Au、Ag、Al金属,制备出金属-半导体-金属型(MSM)ZnO紫外探测器,测试了五种接触类型的ZnO紫外探测器(Au-ZnO-Au、Ag-ZnO-Ag、Au-ZnO-Al、Ag-ZnO-Al、Al-ZnO-Al)在365nm紫外光光照前后的I-V特性曲线。实验表明Au-ZnO-Au 型、Ag-ZnO-Ag型的探测器的光电流是暗电流的100 万倍,因此,Au-ZnO-Au型、Ag-ZnO-Ag型的ZnO紫外探测器性能比Au-ZnO-Al、Ag-ZnO-Al、Al-ZnO-Al型的优越。ZnO材料的电阻率对ZnO紫外探测器的光电流有较大的影响。在相同偏压下,电阻率越大,探测器的光电流越小。ZnO ultraviolet(UV) detectors with Metal-Semiconductor-Metal(MSM) structure were fabricated by the vacuum evaporation of Au, Ag, and Al on the n-type ZnO single crystal, which was grown with hydrothermal synthesis method. Five types of MSM ZnO detectors(Au-ZnO-Au, Ag-ZnO-Ag, Au-ZnO-Al, Ag-ZnO-Al,Al-ZnO-Al) were illuminated with 365 nm UV light respectively, and their corresponding I-V(Current-Voltage) characteristics were measured. The UV photocurrent values for Au-ZnO-Au and Ag-ZnO-Ag detectors were 1x106 times than their dark current values, and these facts imply that the Au-ZnO-Au and Ag-ZnO-Ag detectors were rather good UV detectors compared to Au-ZnO-Al, Ag-ZnO-Al, Al-ZnO-Al detectors. The photocurrent of the MSM ZnO detectors was also sensitive to the cubic resistance of the ZnO crystal. And it’s found that the higher resistance rate the ZnO crystal the smaller photocurrent value the detector under the same working voltage. 相似文献
We report on the substantial persistent photoconductivity (PPC) response exhibited by the zinc oxide (ZnO) nanorod-based ultraviolet (UV) photodetection system. An increase in photocurrent and, hence, rise in PPC was observed for larger UV exposure times at regular intervals. Triggered by quantum efficiency, the increment in sustained conduction band electrons is proposed as the main reason behind the increased photocurrent response. In contrast, the trap centers located below the conduction band are expected to slow down the recombination rate, which accounts for the rise in PPC. The lowering of PPC upon annealing suggests the surface dependent nature of the PPC. The growth and decay mechanism of PPC has a direct relevance while assessing figure of merit of prototype nanostructure-based optical sensor and UV photodetectors. 相似文献
The ultra-violet(UV) detection has a wide application in both civil and military fields.ZnO is recognized as one of ideal materials for fabricating the UV photodetectors due to its plenty of advantages,such as wide bandgap,low cost,being environment-friendly,high radiation hardness,etc.Moreover,the alloying of ZnO with MgO to make ZnMgO could continually increase the band gap from ~ 3.3 eV to ~ 7.8 eV,which allows both solar blind and visible blind UV radiation to be detected.As is well known,ZnO is stabilized in the wurtzite structure,while MgO is stabilized in the rock salt structure.As a result,with increasing the Mg content,the crystal structure of ZnMgO alloy will change from wurtzite structure to rock salt structure.Therefore,ZnMgO photodetectors can be divided into three types based on the structures of alloys,namely,wurtzite-phase,cubic-phase and mixed-phase devices.In this paper,we review recent development and make the prospect of three types of ZnMgO UV photodetectors. 相似文献
We report fabrication and characterization of metal-semiconductor-metal photoconductive detectors based on Al-doped ZnO thin films fabricated by radio frequency magnetron sputtering.Optical and structural properties of the thin films were characterized using various techniques.At 6 V bias,a responsivity higher than 4 A/W in the wavelength shorter than 350 nm was obtained,and this responsibility dropped quickly and reached the noise floor in the visible region.Transient response measurement revealed that the... 相似文献
We propose a simple method to fabricate laterally-grown ZnO-nanowire photodetectors on glass substrates. It was found that cutoff of the fabricated photodetector occurred at 360 nm with a transition region of only 30 nm. With an incident light wavelength of 350 nm and an applied bias of 0.1 V, it was found that measured responsivity of the photodetector was 6.04×10−3 A/W with an ultraviolet-to-visible rejection ratio larger than 600. 相似文献
A high‐performance UV photodetector (PD) based on a p‐Se/n‐ZnO hybrid structure with large area (more than 1×1 cm) is presented in this study. The device is theoretically equivalent to a parallel‐connection circuit for its special structure and shows multifunction at different voltage bias, which means the output signal can be tailored by an applied voltage. The Se/ZnO PD shows binary response (positive and negative current output under on/off periodical light illumination) under small reverse bias (–0.05 V and –0.1 V) which efficiently reduces the negative effect of noise signal in weak‐signal detection applications. At zero bias, with the aid of a p‐n heterojunction, a high on/off ratio of nearly 104 is achieved by this device at zero set bias under 370 nm (∼0.85 mW cm−2) illumination and this on/off ratio can be achieved in 0.5 s. The device also shows a fast speed with rise time of 0.69 ms and decay time of 13.5 ms measured by a pulse laser, much faster than that of a pure ZnO film. The Se/ZnO PD in this research provides a new pathway to fabricate multifunctional high‐speed, high signal‐to‐noise ratio, high detectivity and high selectivity UV photodetectors.
Orderly aligned ZnO nanorod arrays were grown by the ultrafast laser assisted ablation deposition method. These nanorod arrays were further used to make efficient p-n heterojunction photodetector arrays, which have the potential to have nanoscale spatial resolution for imaging, unique incident polarization discrimination capability, and much improved quantum efficiency as well as detection sensitivity. Both front- and back-illumination photodetection schemes were demonstrated by growing those ZnO nanorod arrays on p-type silicon and p-type Zn0.9Mg0.1O-coated Al2O3 (0 0 0 1) substrates, respectively. Typical diode rectification behavior and photosensitivity were observed in both designs through I-V and photocurrent measurements. 相似文献
Nanostructures formed by Au nanoparticles on ZnO thin film surface are of interest for applications which include medical implants, gas-sensors, and catalytic systems. A frequency tripled Nd:YAG laser (λ = 355 nm, τFWHM ∼ 10 ns) was used for the successive irradiation of the Zn and Au targets. The ZnO films were synthesized in 20 Pa oxygen pressure while the subsequent Au coverage was grown in vacuum. The obtained structures surface morphology, crystalline quality, and chemical composition depth profile were investigated by acoustic (dynamic) mode atomic force microscopy, X-ray diffraction, and wavelength dispersive X-ray spectroscopy. The surface is characterized by a granular morphology, with average grain diameters of a few tens of nanometers. The surface roughness decreases with the increase of the number of laser pulses applied for the irradiation of the Au target. The Au coverage reveals a predominant (1 1 1) texture, whereas the underlying ZnO films are c-axis oriented. A linear dependence was established between the thickness of the Au coverage and the number of laser pulses applied for the irradiation of the Au target. 相似文献
