替代衬底上的碲镉汞长波器件暗电流机理

基于暗电流模型, 通过变温I-V分析长波器件(截止波长为9~10 μm)的暗电流机理和主导机制.实验对比了不同衬底、不同成结方式、不同掺杂异质结构与暗电流成分的相关性.结果表明, 对于B+离子注入的平面结汞空位n+-on-p结构, 替代衬底上的碲镉汞(HgCdTe)器件零偏阻抗(R0)在80 K以上与碲锌镉(CdZnTe)基碲镉汞器件结阻抗性能相当.但替代衬底上的HgCdTe因结区内较高的位错, 使得从80 K开始缺陷辅助隧穿电流(Itat)超过产生复合电流(Ig-r), 成为暗电流的主要成分.与平面n+-on-p器件相比, 采用原位掺杂组分异质结结构(DLHJ)的p+-on-n台面器件, 因吸收层为n型, 少子迁移率较低, 能够有效抑制器件的扩散电流.80 K下截止波长9.6 μm, 中心距30 μm, 替代衬底上的p+-on-n台面器件品质参数(R0A)为38 Ω·cm2, 零偏阻抗较n-on-p结构的CdZnTe基碲镉汞器件高约15倍.但替代衬底上的p+-on-n台面器件仍受体内缺陷影响, 在60 K以下较高的Itat成为暗电流主导成分, 其R0A相比CdZnTe基n+-on-p的HgCdTe差了一个数量级.

Abstract

The dark current characteristics of long-wavelength HgCdTe were analyzed for three types of devices. By I-V measurement under different temperatures, the dominant dark currents of each device were clarified at different temperatures. It is demonstrated that the dark current of B+-implanted n+-on-p planar junction on silicon substrate is comparable with that on bulk cadmium zinc telluride (CdZnTe) substrate above 80 K. However, the trap-assisted tunneling current becomes dominant below 80 K due to the high density of dislocations. Compared with n+-on-p junctions, the p+-on-n double-layer heterojunction inhibits the diffusion current effectively, which is good matched with the calculation result with the parameters, derived from I-V curve fitting. This p+-on-n diode has a R0A value of 38 Ω·cm2 at 80 K, for the cut-off wavelength of 9.6 μm, while that of the n+-on-p diode on bulk CdZnTe is 2.5 Ω·cm2. Below 60 K, the dislocations make the R0A value of the p+-on-n diode an order of magnitude lower than that of the n+-on-p diode on CdZnTe.

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赵真典, 陈路, 傅祥良, 王伟强, 沈川, 张彬, 卜顺栋, 王高, 杨凤, 何力. 替代衬底上的碲镉汞长波器件暗电流机理[J]. 红外与毫米波学报, 2017, 36(2): 186. ZHAO Zhen-Dian, CHEN Lu, FU Xiang-Liang, WANG Wei-Qiang, SHEN Chuan, ZHANG Bin, BU Shun-Dong, WANG Gao, YANG Feng, HE Li. Dark current mechanism in long-wavelength HgCdTe infrared detectors on alternative substrates[J]. Journal of Infrared and Millimeter Waves, 2017, 36(2): 186.

替代衬底上的碲镉汞长波器件暗电流机理

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