高量子效率InAs/GaSb II类超晶格谐振腔长波红外探测器研究

Because of its excellent infrared detecting properties, InAs/GaSb type II superlattice infrared detector becomes a research hotspot around the world. Especially, long wavelength large area focal plane arrays become critical components in our country. Facing to the relative low quantum efficiency problem of type II superlattice infrared detector, considering the internal and external quantum efficiency, we create a resonant cavity enhanced InAs/GaSb type II superlattice infrared detector structure which is commonly used in semiconductor lasers. To improve the external quantum efficiency of InAs/GaSb type II superlattice infrared detectors, we will simulate the optical structure of superlattice resonant cavity, analyze the surface reflection inhibition mechanism of resonant cavity structure and design a resonant cavity structure working by which the surface reflectance of superlattice detectors will reduce to zero. To improve the internal quantum efficiency, we will deeply study the intrinsic relationship between the absorption region thickness and diffusion length of the superlattice resonant cavity, solve the key problem of how diffusion length limits the device quantum efficiency, and design a resonant cavity structure by which the quantum efficiency can break through the diffusion length limits. Combining with the superlattice energy band design, we will introduce the dark current suppression sturcture in the resonant cavity structure including electronic and hole barrier. We will design and prepare a 12.5 micron working wavelength superlattice resonant cavity detector and finally achieve a high quantum efficiency.

InAs/GaSb II类超晶格以其优异的红外探测性能，近年来国内外研究的一个热点。尤其是长波大面阵的超晶格探测器更是目前国家迫切需求的关键核心元器件。本项目针对超晶格探测器量子效率欠佳的关键问题，从内外量子效率两个角度同时出发，借鉴激光器中常用的谐振腔结构，创造性地提出了高量子效率InAs/GaSb II类超晶格谐振腔吸收增强型探测器研究方案。对超晶格谐振腔的光学结构进行模拟计算，分析谐振腔结构对超晶格探测器表面反射抑制机理，设计在工作波段表面零反射的超晶格谐振腔器件结构，实现器件外量子效率的提升；对超晶格谐振腔吸收区厚度与扩散长度的深入研究，解决扩散长度限制器件量子效率的关键问题，设计突破扩散长度限制的谐振腔超晶格探测器结构，提升器件的内量子效率。最后结合超晶格能带设计，在谐振腔中引入电子势垒和空穴势垒作为暗电流抑制结构。研制出工作中心波长为12.5微米的高量子效率超晶格谐振腔探测器。

本研究针对超晶格红外探测器中量子效率较低的问题展开。从探测器外量子效率和内量子效率两个方面展开了研究。本研究将半导体激光器常用的谐振腔结构引入到超晶格红外探测器中。为了提升超晶格探测器的外量子效率，本研究设计了谐振腔结构的超晶格探测器，在谐振腔镜面反射的作用下，使得器件在工作波长处探测器内光子到外部的反射率降到零，从而提升该波长处探测器的量子效率。为了提升超晶格探测器的内量子效率，研究了吸收区厚度与探测器少子扩散长度的关系，通过谐振腔的共振效应突破了吸收区厚度对量子效应的限制。模拟并分析了超晶格吸收区各项参数对器件光谱响应的影响，获得了间接测试吸收区材料折射率和吸收系数的方法。在谐振腔长波器件能带中引入了电子势垒和空穴势垒，以抑制长波探测器的暗电流。开发了针对GaSb衬底的剥离技术。成功研制出了波长为12微米的长波谐振腔结构探测器。其在8μm处量子效率为67.9%，在10μm处量子效率为51.3%。谐振腔结构被作为一个高量子效率的探测器结构被应用于长波探测器研制当中。最后，利用该结构研制出了长波焦平面探测器。