Qiu Weicheng, Hu Weida, Lin Chun, Chen Xiaoshuang, Lu Wei
Opt Lett. 2016 Feb 15;41(4):828-31. doi: 10.1364/OL.41.000828.
Long-wavelength (especially >12 μm) focal plane array (FPA) infrared detection is the cutting edge technique for third-generation infrared remote sensing. However, dark currents, which are very sensitive to the growth of small Cd composition HgCdTe, strongly limits the performance of long wavelength HgCdTe photodiode arrays in FPAs. In this Letter, 12.5 μm long-wavelength HgCdTe (x≈0.219) infrared photodiode arrays are reported. The variable-area and variable-temperature electrical characteristics of the long-wavelength infrared photodiodes are measured. The characteristics of the extracted zero-bias resistance-area product (l/RA) varying with the perimeter-to-area (P/A) ratio clearly show that surface leakage current mechanisms severely limit the overall device performance. A sophisticated model has been developed for investigating the leakage current mechanism in the photodiodes. Modeling of temperature-dependent I-V characteristic indicates that the trap-assisted tunneling effect dominates the dark current at 50 K resulting in nonuniformities in the arrays. The extracted trap density, approximately 10-10 cm, with an ionized energy of 30 meV is determined by simulation. The work described in this Letter provides the basic mechanisms for a better understanding of the leakage current mechanism for long-wavelength (>12 μm) HgCdTe infrared photodiode arrays.
长波长（尤其是大于12μm）焦平面阵列（FPA）红外探测是第三代红外遥感的前沿技术。然而，对小镉组分HgCdTe生长非常敏感的暗电流，严重限制了FPA中长波长HgCdTe光电二极管阵列的性能。在本信函中，报道了12.5μm长波长HgCdTe（x≈0.219）红外光电二极管阵列。测量了长波长红外光电二极管的可变面积和可变温度电学特性。提取的零偏置电阻-面积积（l/RA）随周长与面积（P/A）比变化的特性清楚地表明，表面漏电流机制严重限制了整体器件性能。已开发出一个复杂模型来研究光电二极管中的漏电流机制。对温度依赖的I-V特性进行建模表明，在50K时陷阱辅助隧穿效应主导暗电流，导致阵列出现不均匀性。通过模拟确定了提取的陷阱密度，约为10-10cm，电离能为30meV。本信函中描述的工作为更好地理解长波长（大于12μm）HgCdTe红外光电二极管阵列的漏电流机制提供了基本原理。
