AlGaN纳米线的制备、组装及其紫外探测器研究

Ultraviolet(UV) photodetectors have imprtant applications ranging from space astronomical observation to detecting for planets, satellites and earth resources.Semiconductor nanomaterial UV photodetectors which own advantages of light weight, small operation voltage, low power consumption and high resolution are suitable for space astronomical observation and loading by spacecraft or orbit satellites. This research contents are as follows: the growth of AlGaN nanowires with different ratio of Al atoms to Ga atoms by chemical vapor deposition; direct assembly of AlGaN nanowires by combining micro-fluidic alignment with dielectrophoresis; the preparation of photodetectors based on single AlGaN nanowire with the structures of source, drain and gate electrodes, and preparing large area photodetectors with parallel arrays of AlGaN nanowires as active layers and superlong Ag nanowires as transparent top electrodes; both types of photodetectors are characterized through dark current, photocurrent, responsitivity, response time and detectivity so as to study theoretically the photo-absorption of nanowires and carriers transport mechanism; obtaining the prototype photodetectors of AlGaN nanowires with the optimum gain of photocurrent.The achievements of this research will provide theoretical and experimental bases for next designing and fabricating focal plane array of AlGaN nanowire ultraviolet photodetector.

紫外探测器在空间天文，对行星和卫星及对地球表面探测都有重要应用。半导体纳米材料紫外探测器具有体积小、重量轻、工作电压很低、能耗小、分辨率高等优点，非常适宜于空间天文应用和外层空间搭载。本项目用CVD生长不同Al、Ga成份比的AlGaN纳米线；用微流及电泳力技术进行AlGaN纳米线组装研究；制备具有源、漏、栅三电极结构的单根纳米线探测器，同时制备大量平行排列的AlGaN纳米线为有源区和超长Ag纳米线为上透明电极的大面积探测器；对制备的纳米探测器进行暗电流、光电流、响应度、响应时间、探测率等测试，进行纳米线光吸收及载流子输运相关机理研究；最终获得性能优化的AlGaN纳米线紫外探测器。通过对纳米线进行微流及电泳力操作从而获得纳米线组装技术为以后研制纳米线紫外探测器焦平面阵列提供坚实的理论和实验基础。

本项目用CVD、PVD方法成功生长了AlGaN、ZnS等宽禁带半导体一维纳米材料（纳米线或纳米管）；对一维纳米材料生长具有重要作用的催化剂Ni、Au和Pd纳米颗粒退火进行了较为深入的研究；对一维纳米材料生长机理进行了较为系统的研究。首次采用液滴蒸发辅助法组装一维纳米材料，得到较好的平行排列结果。以半导体一维纳米材料为有源区，Ag纳米线或Cu纳米线为电极，成功制备了三种不同结构的紫外探测器；其中全纳米线异质结紫外探测器响应波长254纳米，探测器灵敏度为1.375 ×10的3次方，探测率达到1.2×10的11次方 Jones；非对称性金属-半导体-金属结构（MSM）自供电紫外探测器，在偏压为零时，探测灵敏度比目前报道的相同材料有源区的加偏压时的光电探测器最好结果高1 个数量级，响应速率也快 1 个数量级。成功制备了具有源、漏电极的单根纳米管光探测器，其灵敏度为2.022 ×10的3次方,光响应度为1.17×10的7次方A/W。