pBp型II类超晶格长波红外探测材料的界面结构调控及器件制备研究

Type II InAs/GaSb superlattices detectors are photovoltaic device based on pin structure, so the trap assisted tunneling current in the depletion region and the leakage current at the mesa lateral surface are high which degrade the overall device performance. The pBp structure of photoconductive infrared detection has subband structure with less micro depletion region and embedded device structure type, which eliminates the defect assisted tunneling current and surface leakage current from the mechanism. This project uses the P type InAs/GaSb superlattice as a light absorption layer (p layer) and InAs/AlSb superlattice as the barrier layer (B layer) for preparing pBp type minor (electrons) infrared detector. By establishing the theoretical model, the effects of superlattice period, layer thickness, strain and other parameters on B/p band gap, get "zero" band structure parameters. Interface characteristic, behavior and carrier transport property of detector materials are studied. The influence mechanism of B/p interface structure on carrier transport and dark current are revealed; Low defects growing mechanism of materials and embedded structure of the detector are researched.

InAs/GaSb II型超晶格红外探测器多采用pin型台面结构，其耗尽区内缺陷辅助隧穿电流以及台面周边的漏电流是探测器暗电流的主要成分，限制了探测器特别是长波红外探测器的性能。pBp结构少子光导型红外探测具有微耗尽区的能带结构和埋入式的器件结构，这样从机制上消除了缺陷辅助隧穿电流和表面漏电流。本项目采用p型InAs/GaSb超晶格作为红外光吸收层(p层)和InAs/AlSb超晶格作为势垒层(B层)制备pBp型少子（电子）长波红外探测器。通过建立理论模型，研究超晶格周期、子层厚度、应变等参数对B/p带阶的影响，得到"零"带阶的结构参数；研究多层异质探测材料的界面特性、界面行为及载流子输运特性，揭示B/p界面结构对载流子输运和暗电流的影响机理；开展失配体系多层异质探测材料的低缺陷生长机理研究，探索新型pBp少子光导探测器"埋入式"结构的器件工艺。

本项目的目的是利用pBp结构的InAs/GaSb II类超晶格材料制备长波红外探测器，重点进行界面结构调控及器件的制备研究。经过系统的研究，我们得到以下重要结果：1）获得低缺陷密度的InAs/GaSb超晶格材料及优化生长条件；2）获得与GaSb衬底完全匹配的InAsSb和 InAs/InAsSb 超晶格材料，获得核心生长参数；3）发现了刻蚀对材料形貌以及表面结构和电子状态的影响机理，并制备出原型器件；4）研究了多层异质探测材料的界面特性、界面行为及载流子输运特性，揭示出界面结构对载流子输运和暗电流的影响机理；5）对原型探测器进行系统的性能测试，获得探测器的核心参数。所获得的重要研究结果对进一步提高II类超晶格的器件质量、实现中长双色红外探测器具有非常重要的作用。