GaN基p-i-n型紫外探测器的制备与性能研究

发布时间：2018-04-16 20:57

本文选题：氮化镓 + 紫外探测器　；参考：《江南大学》2015年硕士论文

【摘要】：III族氮化物半导体氮化镓(Ga N)具有宽禁带、直接带隙、热稳定性和化学稳定性高等优势,是制备紫外探测器的理想材料。Ga N基紫外探测器具有能耗低、体积小、抗辐射能力强等优点,在军民领域都具有重要的应用价值,已成为Ga N基光电器件研究的一个热点方向。但是,由于Ga N材料缺乏高质量的同质单晶衬底,而异质外延的Ga N中又常常存在高密度位错等结构缺陷,严重限制了高性能Ga N基紫外探测器的开发和应用。寻找能有效降低Ga N外延层缺陷密度的方法,对提高器件的性能有重要的意义。论文首先回顾了Ga N基紫外探测器的研究现状,指出了存在的问题,然后介绍了Ga N材料的基本性质和制备方法,详细描述了几种常用Ga N基紫外探测器的结构和工作原理,以及表征探测器性能的主要参数。在此基础上,开展了下述三部分的研究工作。1、为了降低Ga N材料中的缺陷密度,提高外延层的质量,在图形化蓝宝石衬底(patterned sapphire substrate,PSS)上制备了薄p型层厚度(60 nm)的Ga N基p-i-n型紫外探测器。X光衍射结果表明,与生长在标准蓝宝石衬底上的外延层相比,生长在PSS上的外延层具有更低的缺陷密度。另外,为方便比较探测器的性能,还在PSS上制备了Ga N基的肖特基型紫外探测器。2、为了评价探测器的性能,设计并搭建了一套光谱响应测试系统。为满足测试精度的要求,对系统存在的噪声问题进行了分析、排除,包括将环形灯的开关移至屏蔽箱外,替换源表与探针之间的连接线,将探针台、屏蔽箱与源表接同一个地,优化后整个系统的噪声降到10-12数量级,可满足测试的需求。另外,还研究了光谱系统的光功率问题,即当光传至测试器件时,光衰减严重、器件的光响应不明显的问题。通过使用紫外光纤,并采用万向磁力座使光纤尽可能地靠近器件,有效降低了光功率的衰减,为探测器的性能分析提供了满意的测试平台。3、对制备的Ga N基紫外探测器进行了性能测试和分析。结果表明,PSS上薄p型层的p-i-n型探测器具有较低的暗电流,在深紫外波段也保持着良好的量子效率。将其与肖特基型探测器进行比较,发现两者的性能基本相当。但是,肖特基型探测器的器件面积较大,所以其暗电流比p-i-n型的高。在实际应用中,肖特基型紫外探测器容易受耗尽区宽度和势垒高度的限制,p-i-n型紫外探测器在抑制暗电流方面更有优势。
[Abstract]:III nitride semiconductor gallium nitride (gan) has the advantages of wide band gap, direct band gap, high thermal and chemical stability, etc. It is an ideal material for preparing UV detector with low energy consumption and small volume.Because of its strong anti-radiation ability, it has important application value in military and civilian fields, and has become a hot research direction in the research of gan based optoelectronic devices.However, due to the lack of high quality homogeneous single crystal substrates in gan materials, and the structural defects such as high density dislocations in heteroepitaxial gan, the development and application of high performance gan based UV detectors are seriously restricted.It is very important to find a method to reduce the defect density of gan epitaxial layer.Firstly, this paper reviews the research status of gan based UV detectors, points out the existing problems, then introduces the basic properties and preparation methods of gan materials, and describes in detail the structure and working principle of several commonly used gan based UV detectors.And the main parameters to characterize the performance of the detector.In order to reduce the defect density in gan material and improve the quality of epitaxial layer, the following three parts of research work have been carried out in order to reduce the defect density and improve the quality of the epitaxial layer.Gan based p-i-n UV detectors were fabricated on patterned sapphire substratePSS on patterned sapphire substrates. The results of X-ray diffraction show that compared with the epitaxial layers grown on standard sapphire substrates, gan based p-i-n UV detectors with a thickness of 60 nm have been prepared.The epitaxial layer grown on PSS has lower defect density.In addition, in order to compare the performance of the detector, the Schottky type UV detector of gan base was fabricated on PSS. In order to evaluate the performance of the detector, a spectrum response testing system was designed and built.In order to meet the requirements of testing accuracy, the noise problems in the system are analyzed and eliminated, including moving the switch of the ring lamp outside the shield box, replacing the connection line between the source table and the probe, connecting the probe table, shielding box and source meter to the same place.After optimization, the noise of the whole system is reduced to 10-12 order of magnitude, which can meet the requirements of the test.In addition, the optical power problem of the spectral system is studied, that is, when the light is transmitted to the test device, the optical attenuation is serious and the optical response of the device is not obvious.By using ultraviolet fiber and universal magnetic pedestal to make the optical fiber as close as possible to the device, the attenuation of optical power is effectively reduced.A satisfactory testing platform. 3 is provided for the performance analysis of the detector. The performance of the prepared gan based UV detector is tested and analyzed.The results show that the thin p-type p-i-n detector has low dark current and good quantum efficiency in the deep ultraviolet band.Compared with Schottky detector, it is found that the performance of the two is basically the same.However, the Schottky detector has a larger area, so its dark current is higher than that of p-i-n.In practical application, Schottky type UV detector is easy to be limited by depletion zone width and barrier height. The p-i-n type UV detector has more advantages in suppressing dark current.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN23

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