Ⅲ族氮化物紫外探测器及其研究进展

文中简单介绍了紫外波段光电探测的基本特点,包括各波段特点、大气吸收等,并粗略 介绍了紫外探测的部分应用。然后对Ⅲ族氮化物宽禁带紫外探测器材料体系的研究进展进行了回顾,重点介绍了包括P型材料的制备、金属半导体接触、材料的蚀刻等方面;最后,对国内外近期的紫外探测器特别是紫外焦平面器件的研究进展作了一些评述。     

GaN基紫外探测器

随着GaN基紫外材料的日益成熟,GaN基紫外探测器发展迅速,被认为是和发光二极管、激光器同样重要的器件。本文讨论了紫外探测的意义,介绍了国内外近期研制的各种器件结构的GaN基紫外探测器和紫外焦平面。     

AIGaN紫外探测器及其应用

AlGa基紫外探测器具有量子效率高,工作电压低并能够通过调节组分改变相应波段,在用于多光谱成像时能减少滤光片的使用,提高系统效率,因此成为国内外研究的热点.介绍了AlGaN紫外探测器的发展现状,并以国产AIGaN日盲/可见盲双波段探测器组件为核心建立了演示成像系统.利用此系统设计完成了多种光照条件下目标的成像实验,并且介绍了实验结果.     

GaN p-i-n紫外探测器的研制

研制了一种GaN p-i-n型单元器件,详细地讨论了该器件的制备工艺,并对该器件进行了光电性能测试.测试结果表明,器件的正向开启电压在2 V左右,零偏动态电阻R0约为1010～1011 Ω,最大峰值响应率在365 nm处为0.18～0.21 A/W,器件的上升响应时间和下降时间分别为2.8和13.4 ns.     

A1GaN／GaN MSM紫外探测器特性

在蓝宝石衬底上,用金属有机物气相沉积(MOCVD)法外延生长AlGaN／GaN异质结样品。溅射Ti／Al／Ni／Au和Ni／Au金属膜,在氮气气氛中高温快速退火,分别与样品形成欧姆接触和肖特基接触。随着退火时间的增加,金属一半导体金属(MSM)结构的I-V特性曲线保持良好的对称性,但C-V曲线逐渐失去其对称性。MSM探测器的紫外响应曲线具有良好的对比度和选择性,出现明显的光电导增益效应。     

GaN基可见盲紫外探测器及其研究进展

介绍了GaN基的3种可见盲紫外光探测器：p-i-n结、肖特基势垒和金属-半导体-金属紫外光探测器，并对其工作原理、特性和发展现状进行了综述。     

基于GaN的紫外探测器线列

美国哥达德空间飞行中心最近研制了一种基于氮化镓的紫外探测器线列,这种紫外探测器线列对大部分可见光光谱是盲目的,其截止波长为370 nm.它能在存在大量可见光辐射的情况下进行紫外光成像,而无需用大面积的挡板来抑制杂散光或者用昂贵的滤光片来阻挡可见光.该GaN探测器列阵的体积、重量及功耗比现在用于深测紫外光的光电倍增管和微道板低一个数量级,它还能够在较低的电压下工作.此外,GaN材料比较坚固,用它制备探测器比较容易.     

GaN/6H-SiC紫外探测器的光电流性质研究

本文研究了以金属有机物化学气相沉积方法生长在６Ｈ－ＳｉＣ衬底上的ＧａＮ外延薄膜制成的光导型紫外探测器的光电流性质．通过对其光电流谱的测量，获得了ＧａＮ探测器在紫外波段从２５０～３６５ｎｍ近于平坦的光电流响应曲线，并且观察到在～３．４ｅＶ带边附近陡峭的截止边，即当光波长在从３６５ｎｍ变到３７５ｎｍ的１０ｎｍ区间内，光电流信号下降了３个数量级．在３６０ｎｍ波长处，我们测得ＧａＮ探测器在５Ｖ偏压下光电流响应度为１３３Ａ／Ｗ，并得到了其响应度与外加偏压的关系．通过拟合光电流信号强度与入射光调制频率的实验数据     

GaN基半导体太阳盲区紫外探测器研究进展

基于半导体紫外光探测器的基本类型，在对半导体紫外探测器的研发历史进行简要回顾的同时，综述了各种形式GaN基紫外探测器的研究开发现状，并报道了GaN基宽带半导体太阳盲区紫外光探测器研究新进展。     

GaN基RCE紫外探测器

本文分析了RCE探测器性能增强的基本原理;推导了布拉格反射镜的反射机理及其反射传输矩阵模型;介绍了MSMRCE紫外光电探测器的结构及其相关性能;指出了GaN基RCE紫外探测器目前所面临的问题以及可能解决的方案。     

高性能背照式GaN/AlGaN p-i-n紫外探测器的制备与性能

研究了GaN/AlGaN异质结背照式p-i-n结构可见盲紫外探测器的制备与性能。GaN/AlGaN外延材料采用金属有机化学气相沉积（MOCVD）方法生长，衬底为双面抛光的蓝宝石，缓冲层为AlN，n型层采用厚度为0.8 μm的Si掺杂Al0.3Ga0.7N形成窗口层，i型层为0.18 μm的非故意掺杂的GaN，p型层为0.15 μm的Mg掺杂GaN。采用Cl2、Ar和BCl3感应耦合等离子体刻蚀定义台面，光敏面面积为1.96×10-3 cm2。可见盲紫外探测器展示了窄的紫外响应波段，响应区域为310~365 nm，在360 nm处响应率最大，为0.21 A/W，在考虑表面反射时，内量子效率达到82％；优质因子R0A为2.00×108 Ω·cm2，对应的探测率D*=2.31×1013 cm·Hz1/2·W-1；且零偏压下的暗电流为5.20×10-13 A。     

Improvement of metal-semiconductor-metal GaN photoconductors

Metal-semiconductor-metal photoconductors made on GaN usually exhibit a slow response time and a low responsivity. We have carried out a systematic study on the performance of the photoconductors made from GaN grown by metalorganic chemical vapor deposition using different growth conditions and have found that both response time and responsivity of the GaN detector are improved when the material is grown using increased ammonia flow rates. The best GaN ultraviolet photoconductive detector shows a response time of 0.3 ms and a responsivity of 3200 A/W at 365 nm under an operation bias of 10 V. We attribute this improvement to the reduction of the point defects in GaN.     

GaN基紫外探测器发展概况

基于宽禁带半导体材料的GaN基紫外探测器由于具有探测波长可调、工艺兼容性好、结构可多型化等优点,已成为近年来的研究热点。介绍了四种不同结构类型的紫外探测器:光导型、肖特基势垒、金属-半导体-金属、p-i-n结,并回顾了GaN基紫外探测器的的研究历程。     

The effect of transparent conductive nanocrystalline oxide thin layer on performance of UV detectors fabricated on Fe-doped GaN

Two kinds of metal-semiconductor-metal (MSM) Schottky UV detectors with and without an insertion layer of transparent conductive nanocrystalline oxide were fabricated on Fe-doped semi-insulating GaN epilayers. It is found that the optical responsivity of the detectors can be significantly improved by two orders of magnitude by inserting a thin layer of Ga-doped nanocrystalline ZnO (GZO) between metal electrode and Fe-doped GaN. Such improvement is suggested to be associated with the valence-band discontinuities and efficient suppression recombination of traps induced by Fe impurities in GaN due to the insertion of a thin layer of GZO.     

p-GaN-i-GaN/AlGaN multiple-quantum well n-AlGaN back-illuminated ultraviolet detectors

The spectral response of back-surface-illuminated p-GaN-i-GaN/AlGaN multiplequantum well (MQW)-n-AlGaN ultraviolet (UV) photodetector is reported. The structure was grown by molecular-beam epitaxy on a c-plane sapphire substrate. A MQW is introduced into the active region of the device to enhance the quantum efficiency caused by the high absorption coefficient of the two-dimensional (2-D) system. Another advantage of using MQW in the active region is the ability to tune the cutoff wavelength of the photodetector by adjusting the well width, well composition, and barrier height. The zero-bias peak responsivity was found to be 0.095 A/W at 330 nm, which corresponds to 36% quantum efficiency from as-grown p-i-n GaN/AlGaN MQW devices. An anomalous effect, occurring in responsivity as a negative photoresponse in the spectra peaked at 362 nm because of poor ohmic contact to p-type GaN, was also observed. Etching the sample in KOH for 30 sec before fabrication removed the surface contaminants and improved the surface smoothness of the as-grown sample, resulting in significant improvement in the device performance, giving a peak responsivity of 0.12 A/W. The device has a quantum efficiency of 45% at 330 nm without the anomalous negative photocurrent.     

Very high-speed ultraviolet photodetectors fabricated on GaN

We report on the temporal and the frequency response of both metal-semiconductor-metal (MSM) and p-i-n ultraviolet photodetectors fabricated on single-crystal GaN. The best MSM devices show a fast 10–90% rise-time of ∼28 psec under comparatively low ultraviolet excitation of ∼0.1 W/cm² averagerirradiance. The fast-Fourier transform (FFT) of the pulse response data indicates a bandwidth, f_3dB, of ∼3.8 GHz at a reverse bias of 25 V. This agrees well with the direct frequency response measurement value of ∼3.5 GHz. For the p-i-n devices, we measured a rise-time of ∼43 psec at 15 V reverse bias for a 60 μm diameter mesa with 1 μm thick intrinsic region. The FFT of the p-i-n pulse response obtains f_3dB ≈1.4 GHz. Analysis in terms of reverse bias and geometric scaling indicates that the MSM photodetectors are transit-time limited. The p-i-n devices also show evidence of transit-time limited effects based on trends with respect to reverse bias and intrinsic region thickness. However, our larger area p-i-n devices show clear evidence of RC-limited behavior. Modeling of the temporal behavior indicates that a slow component in the time and frequency response data is a consequence of the hole drift velocity. We have also found preliminary evidence of microplasmic effects in the p-i-n devices.     

GaN光电阴极测试与评估技术研究

GaN光电阴极的制备成功与否需用科学手段加以评估.在GaAs光电阴极多信息量测试系统的基础上,增设紫外光源,并对评估软件重新加以编写,设计出GaN光电阴极测试评估系统.利用该系统测试了GaN光电阴极在制备过程中的Cs源电流、O源电流、光电流和激活室真空度等多个信息量,并利用激活后的光谱响应对阴极进行了评估,实现了对GaN光电阴极性能的客观评价.     

平面型GaN p-n结探测器的制备与性能

采用金属有机物化学气相沉积(MOCVD)方法在蓝宝石衬底上制备了p-GaN单晶薄膜.高温(＞1100℃)处理及未处理样品的双晶摇摆曲线测试表明高于1150℃会使材料的晶体质量明显变差,这为平面型紫外探测器制备中的部分注入激活条件提供了选择依据.通过TRIM软件优化了注入条件,在选择性注入改型材料上成功制备了平面GaN ...     

AlxGa1−xN/GaN multi-quantum-well ultraviolet detector based on p-i-n heterostructures

We report on characterization of a set of AlGaN/GaN multiple-quantum-well (MQW) photodetectors. The model structure used in the calculation is the p-i-n heterojunction with 20 AlGaN/GaN MQW structures in i-region. The MQW structures have 2 nm GaN quantum well width and 15 nm Al_xGa_1−xN barrier width. The cutoff wavelength of the MQW photodetectors can be tuned by adjusting the well width and barrier height. Including the polarization field effects, on increasing Al mole fraction, the transition energy decreases, the total noise increases, and the responsivity has a red shift, and so the detectivity decreases and has a red shift.