Volume 52 Issue 4
Apr.  2023
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Song Linwei, Kong Jincheng, Zhao Peng, Jiang Jun, Li Xiongjun, Fang Dong, Yang Chaowei, Shu Chang. Research of Au-doped LWIR HgCdTe detector[J]. Infrared and Laser Engineering, 2023, 52(4): 20220655. doi: 10.3788/IRLA20220655
Citation: Song Linwei, Kong Jincheng, Zhao Peng, Jiang Jun, Li Xiongjun, Fang Dong, Yang Chaowei, Shu Chang. Research of Au-doped LWIR HgCdTe detector[J]. Infrared and Laser Engineering, 2023, 52(4): 20220655. doi: 10.3788/IRLA20220655

Research of Au-doped LWIR HgCdTe detector

doi: 10.3788/IRLA20220655
  • Received Date: 2023-01-20
  • Rev Recd Date: 2023-02-25
  • Available Online: 2023-04-14
  • Publish Date: 2023-04-25
  •   Significance   Due to the high quantum efficiency and ultra-wide infrared wavelengths (from SWIR to VLWIR), Mercury cadmium telluride (Hg1xCdxTe, 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·cm2λcutoff=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.
  • [1] Rogalski A. HgCdTe infrared detector material: history, status and outlook [J]. Rep Prog Phys, 2005, 68: 2267-2336. doi:  10.1088/0034-4885/68/10/R01
    [2] Liu Shuning, Tang Qianying, Li Qing. Research progress on local field characterization of mercury cadmium telluride infrared photodetectors [J]. Infrared and Laser Engineering, 2022, 51(7): 20220277. (in Chinese) doi:  DOI:10.3788/IRLA20220277
    [3] Hu W D, Li Q, Cheng X S, et al. Recent progress on advanced infrared photodetectors [J]. Acta Physica Sinica, 2019, 68(12): 120701.
    [4] Sun Quanzhi. Study on preparation technology and properties of Au doped HgCdTe LPE materials with large size and high quality [D]. Shanghai: Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 2012. (in Chinese)
    [5] Li Q, Hu W, Lin C, et al. Dark current characterization of Au and Hg-vacancy hybrid doped p-type epitaxy long-wavelength HgCdTe infrared photodetectors [C]//Proc of SPIE, 2018, 10624: 106240R.
    [6] Ziegler J, Bitterlich H, Bruder R, et al. Large-format MWIR and LWIR detectors at AIM [C]//Proc of SPIE, 2013, 8704: 87042L.
    [7] Lutz H, Breiter R, Figgemeier H, et al. Improved high operating temperature MCT MWIR modules [C]//Proc of SPIE, 2014, 9070: 90701D.
    [8] Breiter R, Figgemeier H, Luta H, et al. Improved MCT LWIR modules for demanding imaging applications [C]//Proc of SPIE, 2015, 9451: 945128.
    [9] Shih H D, Kinch M A, Aqariden F, et al. Development of gold-doped Hg0.79Cd0.21Te for very-long-wavelength infrared detectors [J]. Applied Physics Letters, 2003, 82(23): 4157-4159. doi:  10.1063/1.1581369
    [10] Hu Shangzheng, Guo Mingzhu, Liu Ming, et al. Research on Au-doped HgCdTe epilayer growth by LPE [J]. Laser & Infrared, 2017, 47(7): 838-841. (in Chinese)
    [11] Song Linwei, Kong Jincheng, Li Dongsheng, et al. Au-doped HgCdTe infrared material and device technology [J]. Infrared Technology, 2021, 43(2): 97-103. (in Chinese)
    [12] Ciani A J, Ogut S, Batra I P. Concentrations of native and gold defects in HgCdTe from first principles calculations [J]. Journal of Electronic Materials, 2004, 33(6): 737-741. doi:  10.1007/s11664-004-0075-0
    [13] Antoszewski J, Musca C A, Dell J M, et al. Characterization of Hg0.3Cd0.7Te n-on p-type structures obtained by reactive ion etching induced p to n conversion [J]. Journal of Electronic Materials, 2000, 29(6): 837-840. doi:  10.1007/s11664-000-0234-x
    [14] Sun Q Z, Yang J R, Wei Y F, et al. Characteristics of Au migration and concentration distributions in Au-doped HgCdTe LPE materials [J]. Journal of Electronic Materials, 2015, 44(8): 2773-2778. doi:  10.1007/s11664-015-3735-3
    [15] Wei Yanfeng, Sun Quanzhi, Zhang Juan, et al. Photoelectric characteristics of HgCdTe with Au-doping [J]. Infrared and Laser Engineering, 2021, 50(4): 20200231. (in Chinese) doi:  DOI:10.3788/IRLA20200231
    [16] Reibel Y, Rouvie A, Nedelcu A, et al. Large format, small pixel pitch and hot detectors at sofradir [C]//Proc of SPIE, 2013, 8896: 88960B.
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Research of Au-doped LWIR HgCdTe detector

doi: 10.3788/IRLA20220655
  • Kunming Institute of Physics, Kunming 650223, China

Abstract:   Significance   Due to the high quantum efficiency and ultra-wide infrared wavelengths (from SWIR to VLWIR), Mercury cadmium telluride (Hg1xCdxTe, 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·cm2λcutoff=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.

    • 碲镉汞(Hg1−xCdxTe)材料的禁带宽度可随组分x的变化在0~1.6 eV范围内连续调节,可实现短波至长波红外波段的探测,且具有高量子效率的优势,使碲镉汞焦平面器件成为目前红外光电系统中需求最为迫切、应用最为广泛的关键核心器件,在高端红外探测器领域一直占据着主导地位[1-3]

      碲镉汞焦平面器件主要有n-on-p型和p-on-n型两种器件结构,n-on-p型器件结构具有工艺简单可靠、稳定性较好的优势,被以法国Sofradir为代表的红外公司广泛采用。然而在n-on-p器件中,一般采用本征汞空位P型材料作为吸收层,汞空位本身就是一种深能级缺陷,导致吸收层材料少子寿命低,器件暗电流很难控制在较低水平。研究发现,采用Au(金)掺杂型P型材料代替汞空位型P型材料有助于降低汞空位浓度,降低深能级复合中心密度,提高少子寿命,降低器件暗电流,是提升n-on-p型碲镉汞长波器件整体性能最有效的途径[4-5]

      Au掺杂n-on-p型碲镉汞器件的研制以德国AIM公司为代表,并将Au掺杂作为提升传统汞空位n-on-p型器件性能最有效的方法。德国AIM公司在长波器件方面[6],采用Au掺杂技术研制出了长波1280×1024(15 μm)器件,器件噪声等效温差(NETD)达到30.4 mK,有效像元率达到99.81%。采用Au掺杂技术将中波碲镉汞器件工作温度提升到了160 K,目前AIM公司Au掺杂工艺已非常成熟,工作温度为160 K的640×512 (15 μm pitch)中波高温器件已经实现批量生产[7-8],AIM公司对Au掺杂n-on-p型器件的研究已经达到工程化水平。美国DRS公司研究发现[9],采用非本征Au掺杂原子代替本身作为深能级复合中心的汞空位(VHg),在相同载流子浓度下可明显提高碲镉汞P型材料少子寿命,Au掺杂浓度为7×1015 cm−3的甚长波碲镉汞材料,其少子寿命高达0.82 μs,与本征汞空位材料相比其少子寿命有明显提升,暗电流较常规汞空位型器件降低了一个数量级,有效改善了器件性能。

      华北光电技术研究所、中国科学院上海技术物理研究所、昆明物理研究所都对碲镉汞Au掺杂器件技术做了研究,华北光电技术研究所生长的掺杂浓度为8.3×1015 cm−3的长波Au掺杂材料少子寿命最高可达到0.30 μs,较汞空位P型材料少子寿命提高了一个数量级,R0A较常规汞空位器件工艺提高了5倍[10]。中国科学院上海技术物理研究所采用Au掺杂技术制备了截止波长为14.3 μm的甚长波器件,器件R0A值达到了0.15~0.25 Ω·cm2,相较于常规汞空位器件R0A值0.07 Ω·cm2有明显提升[4]。昆明物理研究所2010年开始Au掺杂碲镉汞器件技术相关研究,经过多年来的持续攻关,先后突破了Au掺杂材料生长技术、电学参数稳定性控制、器件工艺稳定性等关键技术,将长波器件R0A值从31.3 Ω·cm2提升到了363 Ω·cm2以上,暗电流控制水平较常规汞空位型器件降低了一个数量级以上,器件规模从长波256×256逐渐扩展到了1 024×768,实现非本征Au掺杂碲镉汞器件系列化发展,具备长波凝视型焦平面器件的批量化生产能力[11]

      文中基于昆明物理研究所Au掺杂碲镉汞材料稳定性控制、器件暗电流控制等技术,报道了昆明物理研究所非本征Au掺杂长波碲镉汞器件研制进展。

    • 由于Au掺杂原子在碲镉汞材料中为快扩散杂质,其扩散系数约为2.7×10−11 cm−2·s−1,比同为P型掺杂原子As的扩散系数(10−14 cm−2·s−1量级)高近3个量级,在热处理及工艺过程中,很容易往缺陷区及界面扩散富集,因而在Au掺杂器件工艺中,首先需控制Au掺杂材料稳定性[12-13]

      由于富Te液相外延生长的碲镉汞薄膜中会有大量汞空位(VHg)存在,掺杂Au原子在该条件下很容易占据汞格点实现受主掺杂,可实现较高的掺杂浓度材料生长,昆明物理研究所采用富Te水平液相外延技术实现了掺杂浓度可控的Au掺杂长波材料生长。

      Au掺杂碲镉汞材料外延生长后,材料中有较多的汞空位存在,因而此时的原生材料呈现高浓度P型,汞空位起主导作用,需将Au掺杂原生材料进行汞饱和热处理,以填充材料中的汞空位,使材料中Au掺杂原子占主导,呈现P型导电。然而Au掺杂原子为快扩散杂质,热处理过程中趋向于向界面和缺陷处扩散富集,材料内部Au掺杂原子浓度降低,Au掺杂原子的快扩散特点导致热处理后材料电学参数不可控,严重影响外延材料成品率以及后续工艺的稳定性[14-15]

      对于Au原子快扩散特性导致的Au掺杂碲镉汞材料稳定性控制问题,研究发现,热处理时引入一定的汞空位有助于提高Au掺杂原子稳定性,从而提高Au材料碲镉汞材料电学参数控制,热处理后Au掺杂原子沿材料厚度分布如图1所示。热处理后P型碲镉汞外延材料载流子浓度可控制在1.0~4.0×1016 cm−3之间,迁移率可以达到500 cm2/Vs以上,图2所示为实现了稳定性较好的Au掺杂碲镉汞长波材料的制备。

      Figure 1.  Depth distributions of Au atom concentration in Au-doped HgCdTe materials annealed in an Hg-rich state

      Figure 2.  Carrier concentration and mobility of Au-doped HgCdTe materials annealed in an Hg-rich state

    • 器件暗电流是反映探测器本质的特征参数,暗电流的大小决定了器件性能,包括扩散电流Idiff、产生复合电流IG-R、直接隧道电流IBBT、缺陷辅助隧道电流ITAT、碰撞电离电流IIMP和表面漏电流Isurf等类型。总的暗电流等于各项电流之和,如下式所示:

      HgCdTe器件各种暗电流中,扩散电流和产生-复合电流由材料电学性能及复合机制决定,隧道电流与材料缺陷性能有关。扩散电流是PN结空间电荷区两端载流子在电场作用下发生扩散和漂移而形成的电流,是热平衡下由空间电荷区两端少子扩散长度内的载流子所形成的电流。

      载流子浓度相同的情况下,碲镉汞器件的扩散电流与少子寿命成反比,提高材料的少子寿命可降低器件扩散电流。采用非本征Au掺杂原子代替本身就为深能级复合中心的本征汞空位,有助于降低碲镉汞材料中深能级缺陷,提升P型碲镉汞材料少子寿命,降低器件暗电流,达到提升n-on-p型器件性能的目的。

      昆明物理研究所采用Au掺杂技术制备的载流子浓度为1.5×1016 cm−3的Au掺杂长波碲镉汞(10.5 μm@80 K)材料,少子寿命达到0.25 μs,与目前报道的采用相同技术路线材料少子寿命最高水平相当。

      图3为采用非本征Au掺杂技术与本征汞空位型长波256×256 (30 μm pitch)碲镉汞焦平面器件暗电流对比。80 K下截止波长为10.6 μm本征汞空位长波256×256碲镉汞器件暗电流为1980 pA ,而相同温度下截止波长为10.5 μm非本征Au掺杂器件暗电流仅为171 pA,采用Au掺杂技术可有效降低n-on-p型长波焦平面器件暗电流,长波器件的暗电流密度从2.2×10−4 A·cm−2降低至1.9×10−5 A·cm−2,R0A从31.3 Ω·cm2提升到了363 Ω·cm2

      Figure 3.  Dark current distribution of the 256×256 (30 μm pitch) LWIR HgCdTe detectors. (a) Intrinsic VHg doping; (b) Extrinsic Au-doping

      图4为昆明物理研究所制备的Au掺杂长波器件暗电流随工作温度变化图。上下两条趋势线分别为n-on-p器件和p-on-n器件暗电流控制理论值,对比发现非本征Au掺杂器件暗电流水平明显低于本征汞空位n-on-p型器件,并且随着工作温度的升高,Au掺杂长波器件暗电流越接近Rule07 p-on-n型器件理论值,在110 K时Au掺杂长波器件暗电流控制与Rule07 p-on-n器件控制水平接近。

      Figure 4.  Dark current versus temperature for Au-doped LWIR HgCdTe detectors

      图5为昆明物理研究所Au掺杂长波器件暗电流控制水平与国际先进水平对比图,Au掺杂长波器件R0A值较常规汞空位n-on-p型器件提升了至少一个数量级,与p-on-n型器件R0A值控制水平接近,昆明物理研究所Au掺杂长波器件暗电流控制接近国际先进水平,为高性能长波焦平面器件的研制奠定基础。

      Figure 5.  Dark current with Au-doped LWIR HgCdTe detectors

    • 昆明物理研究所基于Au掺杂技术对碲镉汞器件暗电流控制方面的优势,先后研制出了Au掺杂碲镉汞256×256 (30 μm pitch)、640×512 (25 μm pitch)、640×512 (15 μm pitch)等规格型号的长波器件,性能与国外报道的器件水平相当,实现了非本征Au掺杂长波碲镉汞器件系列化发展,达到了批量化的生产水平。几种器件典型性能指标如表1所示。

      Kunming Institute of PhysicsSofradir
      MARSVENUSSCORPIO
      Format256×256640×512640×5121024×768320×256384×288640×512
      Pixel pitch/μm30251510302515
      Cut-off wavelength/μm10.510.39.89.59.59.59.3
      Operating temperature/K77777770808080
      FOVF2F2F2F3F2F2F2
      NETD/mK10.419.123.127.7≤19≤17≤22
      Responsivity non-uniformity3.87%5.45%4.82%4.52%---
      Average peak detectivity2.33×1011 1.86×10111.62×1011 3.45×1011 ---
      Array operability99.90%99.90%99.87%99.79%≥99.70%≥99.50%≥99.80%

      Table 1.  Typical performance parameters of Au-doped LWIR HgCdTe detectors with different scale

    • 昆明物理研究所采用非本征Au掺杂技术研制出的长波30 μm中心距256×256规格器件,F数为2时,截止波长为10.5 μm (77 K)的器件平均峰值探测率大于2.0×1011 cm·Hz1/2·W−1,NETD小于11 mK,有效像元率达到99.9%以上,响应率非均匀性小于5%,典型器件性能参数见表1,如图6(a)为组件实物图,图6(b)为器件信号响应图,图6(c)为器件NETD分布图。

      Figure 6.  LW 256×256 (30 μm pitch) detector. (a) FPA photo; (b) Response signal diagram ; (c) NETD histogram

    • 采用非本征Au掺杂技术研制出的长波25 μm中心距640×512规格器件,当F数为2时,截止波长为10.3 μm (77 K)的器件平均峰值探测率大于1.8×1011 cm·Hz1/2·W−1,NETD小于20 mK,有效像元率达到99.7%以上,响应率非均匀性小于6%,典型器件性能参数如表1所示,图7(a)为组件实物图,图7(b)为器件信号响应图,图7(c)为器件NETD分布图。

      Figure 7.  LW 640×512 (25 μm pitch) detector. (a) FPA photo; (b) Response signal diagram; (c) NETD histogram

    • 采用非本征Au掺杂技术研制出的长波15 μm中心距640×512规格器件,当F数为2时,截止波长为9.8 μm (77 K)的器件平均峰值探测率大于1.5×1011 cm·Hz1/2·W−1,NETD小于25 mK,有效像元率达到99.7%以上,响应率非均匀性小于5%,典型器件性能参数如表1所示,图8(a)为组件实物图,图8(b)为器件信号响应图,图8(c)为器件NETD分布图。

      Figure 8.  LW 640×512 (15 μm pitch) detector. (a) FPA photo; (b) Response signal diagram; (c) NETD histogram

    • 采用非本征Au掺杂技术研制出的长波10 μm中心距1024×768规格器件,当F数为3时,截止波长为9.5 μm (70 K)的器件平均峰值探测率大于3.0×1011 cm·Hz1/2·W−1,NETD小于30 mK,有效像元率达到99.7%以上,响应率非均匀性小于5%,典型器件性能参数如表1所示,图9(a)为组件实物图,图9 (b)为器件信号响应图,图9 (c)为器件NETD分布图。

      Figure 9.  LW 1 024×768 (10 μm pitch) detector. (a) FPA photo; (b) Response signal diagramg; (c) NETD histogram

    • 在前期的研究中,法国Sofradir公司认为,由于Au原子为快扩散杂质原子,可能会对器件长期稳定性有一定的影响[16]。针对该问题昆明物理研究所开展了Au掺杂碲镉汞器件高低温存储、高低温循环(+70~−40 ℃)及长期贮存等稳定性的研究,Au掺杂器件经高低温存储、循环后器件性能无明显变化。图10所示为Au掺杂碲镉汞长波256×256器件NETD和盲元随存储时间变化图,该支组件2015年封装后,在室温下至今贮存时间超过7年,在贮存期间约6个月间隔进行性能测试,试验数据表明Au掺杂器件经历7年长期贮存过程中器件性能无明显变化。

      Figure 10.  NETD and bad pixels versus storage time of Au-doped LWIR HgCdTe 256×256 detector

    • 文中报道了昆明物理研究所多年来在非本征Au掺杂碲镉汞材料和器件方面的研制成果。通过热处理工艺的优化可将Au掺杂碲镉汞材料载流子浓度稳定控制到1.0~4.0×1016 cm−3,提升了Au掺杂碲镉汞材料稳定性;采用非本征Au掺杂原子代替本身就为深能级复合中心的本征汞空位,将10.5 μm截止波长器件的R0A从31.3 Ω·cm2提升到了363 Ω·cm2,有效降低器件暗电流,明显提升了n-on-p型长波器件性能;在此基础上昆明物理研究所实现了从256×256 (30 μm pitch)、640×512 (25 μm pitch)、640×512 (15 μm pitch)、1024×768 (10 μm pitch)规格长波碲镉汞器件批量化生产,实现了非本征Au掺杂长波碲镉汞器件系列化发展,并且Au掺杂器件经历7年以上时间的贮存,性能无明显变化,具有较好的长期稳定性。非本征Au掺杂n-on-p型技术可作为高灵敏度、高分辨率等高性能长波及高工作温度碲镉汞器件研制的一种有效的技术途径。

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