非制冷势垒型InAsSb基高速中波红外探测器

高速响应的中波红外探测器在自由空间光通信和频率梳光谱学等新兴领域的需求逐渐增加。中长波XB_nn势垒型红外光探测器对暗电流等散粒噪声具有显著抑制作用。本文在GaSb衬底上采用分子束外延技术生长了nBn和pBn两种结构的InAsSb/AlAsSb/AlSb中波红外光探测器材料，并通过微纳加工工艺制备了可用于射频响应特性测试的GSG结构探测器。XRD和AFM的测试结果表明，两种结构的外延片都具有较好的晶体质量。器件暗电流测试结果表明，相较于nBn器件，在室温和反向偏压400 mV的工作条件下，直径90 μm的pBn器件表现出更低的暗电流密度0.145 A/cm2，说明该器件在室温非制冷环境下表现出较低的噪声水平。不同台面直径的探测器的暗电流测试表明，pBn器件的表面电阻率低于对照的nBn器件的表面电阻率。另外，根据探测器的电容测试结果，可零偏压工作的pBn探测器具有完全耗尽的势垒层和部分耗尽的吸收区，nBn的吸收区也存在部分耗尽。探测器的射频响应特性表明，直径90 μm的pBn器件的响应速度在室温和3 V反向偏压下可达2.62 GHz，对照的nBn器件的响应速度仅为2.02 GHz，响应速度提升了29.7%，初步实现了在中红外波段下可快速探测的室温非制冷势垒型光电探测器。

Uncooled InAsSb-based high-speed mid-wave infrared barrier detector

The demand for high-speed response mid-wave infrared （MWIR） photodetectors （PDs） is gradually increasing in emerging fields such as free-space optical communication and frequency comb spectroscopy. The XB_nn barrier infrared photodetectors greatly suppress shot noise originated from the device dark current. In this work， InAsSb/AlAsSb/AlSb-based nBn and pBn barrier MWIR PDs were grown on GaSb substrates using molecular beam epitaxy （MBE）. The GSG PDs were fabricated to realize the radio frequency （RF） response testing. X-ray diffraction （XRD） and atomic force microscopy （AFM） results indicate that both epitaxial structures exhibit good crystal quality. The 90 μm diameter pBn PDs exhibit a lower dark current density of 0.145 A/cm2 compared to the nBn PDs operating at room temperature （RT） and a reverse bias of 400 mV， which indicates the uncooled barrier PDs perform with low noise. Capacitance tests reveal that the pBn PDs， operating at zero bias， show a fully depleted barrier layer and partially depleted absorption region， while the nBn absorption region also exhibits partial depletion. RF response characterization demonstrates that the 90 μm diameter pBn PDs achieve 3 dB bandwidth of 2.62 GHz at room temperature and under a 3 V reverse bias， which represents a 29.7% improvement over the corresponding nBn PDs， only achieving 3 dB bandwidth of 2.02 GHz. This signifies a preliminary achievement of uncooled barrier MWIR PDs capable of fast detection.