基于nBn型低暗电流InAs/GaSb超晶格双色红外探测器的研究

Type II InAs/GaSb superlattices have some advantages such as good uniformity, tunable band-gap and low Auger recombination velocity et al. In common application 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. In this project, the dual-color IR detector based on nBn structure using InAs/GaSb superlattices and Al1-xGaxSb film was fabricated. The research includes: the growth of InAs/GaSb superlattices, the relation between Al1-xGaxSb component and the offset at B/n heterojunction by simulation; the influnence of multi-heterojunction on the carrier transportation and dark current; the relation between the hole extract efficiency in MWIR and LWIR absorber and the bias. The device model of dual-color IR detector based on nBn structure will be founded.The low dark current dual-color InAs/GaSb superlattice IR detector based on nBn structure will be fabricated.

InAs/GaSb II型超晶格材料具有均匀性好、能带可调、俄歇复合小等优点，器件多采用pin型台面结构，其耗尽层内缺陷辅助隧穿电流以及台面周边的漏电流是超晶格探测器暗电流的主要成分。nBn型少子光导红外探测器具有平带或微耗尽的能带结构，无表面漏电，上述暗电流被大大抑制。本项目采用两个波段InAs/GaSb超晶格光吸收层(n层)和Al1-xGaxSb势垒层(B层)制备nBn型中、长波双色红外探测器，主要研究中、长波InAs/GaSb超晶格材料的生长，理论计算得到B/n异质结带阶与Al1-xGaxSb组分的依赖关系，揭示多异质界面结构对载流子输运机制和暗电流的影响机理，研究中、长波吸收层少子提取效率随偏压的变化关系，建立nBn型双色红外探测的器件模型，制备出低暗电流nBn型InAs/GaSb超晶格双色红外探测器。

InAs/GaSb II型超晶格材料具有均匀性好、能带可调、俄歇复合小等优点，器件多采用pin型台面结构，其耗尽层内缺陷辅助隧穿电流以及台面周边的漏电流是超晶格探测器暗电流的主要成分。nBn型少子光导红外探测器具有平带或微耗尽的能带结构，无表面漏电，上述暗电流被大大抑制。本项目采用两个波段InAs/GaSb超晶格光吸收层(n层)和Al1-xGaxSb势垒层(B层)制备nBn型中、长波双色红外探测器。通过对InAs/GaSb超晶格和Al1-xGaxSb能带结构的理论计算，获得了势垒层与InAs/GaSb超晶格的带阶参数；揭示了nBn型InAs/GaSb超晶格载流子的输运机制；采用MBE方法生长出符合设计要求的InAs/GaSb超晶格和AlGaSb层，通过优化工艺，实现了nBn型双色探测的原型器件模型；在0.5V偏压下，中波nBn器件暗电流为3×10-4A/cm2，500度黑体响应率和量子效率为0.5A/W和18%。对比PIN台面型中/长波超晶格红外探测器，nBn型红外探测器在暗电流方面有明显的改善。这些结果为开展nBn型低维量子器件的研究提供了理论和实验依据，对高灵敏、宽光谱、快响应、灵巧化的红外器件的发展具有重要意义。