InAs/GaSb超晶格中波红外二极管的Ⅳ特性研究

Current-voltage characteristic of InAs/GaSb superlattice mid-infrared photodiodes

采用分子束外延(MBE)技术,在GaSb衬底上生长了pin结构的InAs(8ML)/GaSb(8ML)超晶格中波红外光电二极管。经过(NH4)2S表面钝化后的Ⅳ特性曲线表明:低的正偏压下,理想因子n在2左右,势垒区的复合电流起主要作用;偏压超过0.14 V时,n在1左右,少子扩散电流占主。表面势垒区中过多的Ⅲ族元素的空位缺陷导致表面出现大量复合中心。采用阳极硫化后,表面漏电大大减小,反偏漏电流密度降低三个数量级,零偏阻抗R0达到106欧姆,R0A达到103量级。

InAs （ 8ML ）/GaSb （ 8ML ） superlattice with p-i-n structure was grown on GaSb substrates by molecular beam epitaxy. IV characteristic under （NH4）2S passivation showed that the ideality factor was near 2 at lower forward bias where recombination current dominated and the factor was near 1 beyond 0.14 V where diffusion current dominated. A large number of combination centers appeared at the surface barrier region originated from the vacancy defects. Compared with （NH4）2S solution treatment, the surface leakage currents density after anode sulfide treatment decreased three orders of magnitude and the zero-bias resistance R0 was measured up to 106 ohms. The figure of merit R0A was up to 103Ωcm-2.