Au掺杂碲镉汞长波探测器技术研究

昆明物理研究所多年来持续开展了对Au掺杂碲镉汞材料、器件结构设计、可重复的工艺开发等研究，突破了Au掺杂碲镉汞材料电学可控掺杂、器件暗电流控制等关键技术，将n-on-p型碲镉汞长波器件品质因子(R₀A)从31.3Ω·cm²提升到了363Ω·cm²(λcutoff=10.5μm@80 K)，器件暗电流较本征汞空位n-on-p型器件降低了一个数量级以上。研制的非本征Au掺杂长波探测器经历了超过7年的时间贮存，性能无明显变化，显示了良好的长期稳定性。基于Au掺杂碲镉汞探测器技术，昆明物理研究所实现了256×256 (30μm pitch)、640×512 (25μm pitch)、640×512 (15μm pitch)、1 024×768 (10μm pitch)等规格的长波探测器研制和批量能力，实现了非本征Au掺杂长波碲镉汞器件系列化发展。

Research of Au-doped LWIR HgCdTe detector

  Significance   Due to the high quantum efficiency and ultra-wide infrared wavelengths (from SWIR to VLWIR), Mercury cadmium telluride (Hg_1?xCd_xTe, MCT) is regarded as the preferred material for high-performance infrared focal plane arrays (FPAs). Compared with p-on-n, n-on-p FPAs have the advantages of simple and reliable manufacturing process. However, in n-on-p FPAs, P-type material with intrinsic mercury vacancy is generally used as the absorption layer. The mercury vacancy belongs to the deep-level defect, which leads to the low carrier lifetime of the absorption layer and the difficulty in controlling the dark current of the device at a low level. Replacing Hg-vacancy with Au (gold) in P-type materials is meaningful to increase minority carrier lifetime, and reduce dark current, which is the most effective way to improve the overall performance of MCT LWIR n-on-p devices. In Kunming Institute of Physics (KIP), the Au-doped MCT devices have been investigated since 2010. After years of continuous research, the key technologies including Au-doped material growth, electrical parameters control, device manufacturing and so on have been successfully broken through, which promoted the fabrication of the high-performance Au-doped n-on-p devices. In this paper, the progress of extrinsic Au-doped MCT LWIR n-on-p technologies in Kunming Institute of Physics was reported comprehensively, which was expected to pave a way for mass production of high-performance LWIR n-on-p FPAs.  Progress   In Kunming Institute of Physics, Te-rich liquid phase epitaxy technology was used to prepare Au-doped LW material. The mercury vacancy concentration was tuned through the heat treatment process with mercury saturation, so as to achieve effective control of electrical parameters. Through the optimization of heat treatment process, the preparation of high-quality Au-doped MCT LW materials was realized, and the carrier concentration can be controlled within 1.0-4.0×1016 cm?3.　　The dark current is a significant parameter that determines the performance of device. The substitution of Au atoms for mercury vacancies is efficient to reduce the deep-level defects in the MCT materials, increase the minority carrier lifetime of P-type materials, and reduce the dark current of devices. The high-performance MCT LWIR devices (10.5 μm@80 K) have been fabricated by Au-doping technology in Kunming Institute of Physics. Compared with the Hg- vacancy n-on-p device, R₀A of the Au-doped LWIR n-on-p device increased from 31.3 Ω·cm2 to 363 Ω·cm2, which was close to the level of p-on-n devices (Rule07) and laid a foundation for the development of high-performance LWIR FPAs.　　Based on the Au-doped technology, LWIR FPAs including 256×256 (30 μm pitch), 640×512 (25 μm pitch), 640×512 (15 μm pitch) and other specifications were fabricated at Kunming Institute of Physics. The performance of these devices was comparable to those reported abroad. The series development and further mass production of non-intrinsic Au-doped MCT LWIR FPAs have been realized. Furthermore, the researches involved high and low temperature storage, high and low temperature cycle (+70-?40 ℃) and long-term storage stability were carried out, and the results show that after 7 years of long-term storage, the performance of the devices have no obvious change.   Conclusions and Prospects  In this paper, the development progress of extrinsic Au-doped MCT materials and devices in Kunming Institute of Physics was reported. The stability of Au-doped HgCdTe materials, dark current control and other key technologies have been broken through up to now. The merit factor (R₀A) has been improved from 31.3 Ω·cm2 to 363 Ω·cm2（λ_cutoff=10.5 μm@80 K） for LWIR HgCdTe focal plane arrays by use of Au-doped technology. The dark current has been reduced by one order of magnitude compared with Hg-vacancy n-on-p devices. And the performance of n-on-p LWIR HgCdTe focal plane arrays has been greatly improved. The performance has not change by storage more than 7 years of the Au-doped HgCdTe device, which shown that the devices have better long-term stablity. Based on this, Kunming Institute of Physics has realized the series development of Au-doped LWIR HgCdTe with a format of 256×256 (30 μm pitch), 640×512 (25 μm pitch), 640×512 (15 μm pitch), and 1 024×768 (10 μm pitch), which has provided a foundation for the mass production of long wave HgCdTe focal plane arrays.