Some results on the molecular-beam epitaxial growth of HgCdTe focusing on the requirements of the 3rd generation infrared focal plane arrays are described. Good uniformity is observed over 75mm HgCdTe epilayers,and th...Some results on the molecular-beam epitaxial growth of HgCdTe focusing on the requirements of the 3rd generation infrared focal plane arrays are described. Good uniformity is observed over 75mm HgCdTe epilayers,and the deviation in cutoff wavelength is within 0. 1μm at 80K. A variety of surface defects are observed and the formation mechanism is discussed. The average density of surface defects in 75mm HgCdTe epiluyers is found to be less than 300cm^-2. It is found that the surface sticking coefficient of As during HgCdTe growth is very low and is sensitive to growth temperature, being only -1 × 10^-4 at 170℃. The activation energy of As in HgCdTe was determined to be 19.5meV,which decreases as （Na - Nd）^1/3 with a slope of 3.1 × 10^-5 meV · cm. The diffusion coefficients of As in HgCdTe of 1.0 ± 0,9 × 10^-16,8 ± 3 × 10^- is, and 1.5 ± 0.9 × 10^-13 cm^2/s are obtained at temperatures of 240,380, and 440℃, respectively under Hg-saturated pressure. The MBE-grown HgCdTe is incorporated into FPA fabrications,and the preliminary results are presented.展开更多
A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15...A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×10^10cm·Hz^1/2·W^-1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.展开更多
In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, t...In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, the different material systems for the devices in this band are outlined. Based on the background, the development of lattice-matched and wavelengthextended InGaAs photodetectors and focal plane arrays, including our continuous efforts in this field, are reviewed. These devices are concentrated on the applications in spectral sensing and imaging, exclusive of optical fiber communication.展开更多
We propose a substrate-free focal plane array （FPA） and the microcantilevers extend from a supporting frame. in this paper. The solid substrate is completely removed, Using finite element analysis, the thermal and m...We propose a substrate-free focal plane array （FPA） and the microcantilevers extend from a supporting frame. in this paper. The solid substrate is completely removed, Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature： the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements： two types of substrate-free FPAs with pixel sizes of 200×200 and 60×60 um^2 are implemented in the proposed infrared detector. The noise equivalent temperature difference （NETD） values are experimentally measured to be 520 and 300 mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30×30 um^2 has a potential of achieving an NETD value of 10 mK.展开更多
HgCdTe多层异质结技术是未来主流红外探测器发展的重要技术方向,在高工作温度、双/多色和雪崩光电管等高性能红外探测器中扮演着重要的角色。近年来基于多层异质结构的Hg Cd Te高工作温度红外探测器得到了快速发展,尤其是以势垒阻挡型...HgCdTe多层异质结技术是未来主流红外探测器发展的重要技术方向,在高工作温度、双/多色和雪崩光电管等高性能红外探测器中扮演着重要的角色。近年来基于多层异质结构的Hg Cd Te高工作温度红外探测器得到了快速发展,尤其是以势垒阻挡型和非平衡工作P~+-π(ν)-N~+结构为主的器件受到了广泛的研究。本文系统介绍了势垒阻挡型和非平衡工作P~+-π(ν)-N~+结构HgCdTe红外探测器的暗电流抑制机理,分析了制约两种器件结构发展的关键问题,并对国内外的研究进展进行了综述。对多层异质结构Hg CdTe红外探测器的发展进行了总结与展望。展开更多
As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum we...As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.展开更多
This paper presents a review of recent advances in quantum well and quantum cascade infrared photodetectors developed in Shanghai Institute of Technical Physics, Chinese Academy of Sciences(SITP/CAS). Firstly, the tem...This paper presents a review of recent advances in quantum well and quantum cascade infrared photodetectors developed in Shanghai Institute of Technical Physics, Chinese Academy of Sciences(SITP/CAS). Firstly, the temperature-and bias-dependent photocurrent spectra of very long wavelength(VLW) GaAs/AlGaAs quantum well infrared photodetectors(QWIPs) are studied using spectroscopic measurements and corresponding theoretical calculations in detail. We confirm that the first excited state, which belongs to the quasi-bound state, can be converted into a quasi-continuum state induced by bias and temperature. Aided by band structure calculations, we propose a model of the double excited states that determine the working mechanism in VLW QWIPs. Secondly, we present an overview of a VLW QWIP focal plane array(FPA)with 320×256 pixels based on the bound to quasi-bound(BTQB) design. The technology of the manufacturing FPA based on the QWIP structures has been demonstrated. At the operating temperature of 45 K, the detectivity of QWIP FPA is larger than 1.4×10^(10) cm·Hz^(1/2)/W with a cutoff wavelength larger than 16 μm. Finally, to meet the needs of space applications, we proposed a new long wavelength quantum cascade detector with a broadband detection ranging from 7.6 μm to 10.4 μm. With a pair of identical coupled quantum wells separated by a thin barrier, acting as absorption regions, the relative linewidth(?E/E) of response can be dramatically broadened to 30.7%. It is shown that the spectral shape and linewidth can be tuned by the thickness of the thin barrier, while it is insensitive to the working temperature. The device can work above liquid nitrogen temperature with a peak responsivity of 63 mA/W and Johnson noise limited detectivity of 5.1×10~9 cm·Hz^(1/2)/W.展开更多
文摘Some results on the molecular-beam epitaxial growth of HgCdTe focusing on the requirements of the 3rd generation infrared focal plane arrays are described. Good uniformity is observed over 75mm HgCdTe epilayers,and the deviation in cutoff wavelength is within 0. 1μm at 80K. A variety of surface defects are observed and the formation mechanism is discussed. The average density of surface defects in 75mm HgCdTe epiluyers is found to be less than 300cm^-2. It is found that the surface sticking coefficient of As during HgCdTe growth is very low and is sensitive to growth temperature, being only -1 × 10^-4 at 170℃. The activation energy of As in HgCdTe was determined to be 19.5meV,which decreases as （Na - Nd）^1/3 with a slope of 3.1 × 10^-5 meV · cm. The diffusion coefficients of As in HgCdTe of 1.0 ± 0,9 × 10^-16,8 ± 3 × 10^- is, and 1.5 ± 0.9 × 10^-13 cm^2/s are obtained at temperatures of 240,380, and 440℃, respectively under Hg-saturated pressure. The MBE-grown HgCdTe is incorporated into FPA fabrications,and the preliminary results are presented.
基金supported by the National Basic Research Program of China(Grant Nos.2013CB932904 and 2011CB922201)the National Special Funds for the Development of Major Research Equipment and Instruments,China(Grant No.2012YQ140005)the National Natural Science Foundation of China(Grant Nos.61274013,61290303,and 61306013)
文摘A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×10^10cm·Hz^1/2·W^-1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0402400)the National Natural Science Foundation of China(Grant Nos.61675225,61605232,and 61775228)the Shanghai Rising-Star Program,China(Grant No.17QA1404900)
文摘In this article, unique spectral features of short-wave infrared band of 1 μm–3 μm, and various applications related to the photodetectors and focal plane arrays in this band, are introduced briefly. In addition, the different material systems for the devices in this band are outlined. Based on the background, the development of lattice-matched and wavelengthextended InGaAs photodetectors and focal plane arrays, including our continuous efforts in this field, are reviewed. These devices are concentrated on the applications in spectral sensing and imaging, exclusive of optical fiber communication.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10732080 and 10627201)the National Basic Research Program of China (Grant No. 2006CB300404)
文摘We propose a substrate-free focal plane array （FPA） and the microcantilevers extend from a supporting frame. in this paper. The solid substrate is completely removed, Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature： the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements： two types of substrate-free FPAs with pixel sizes of 200×200 and 60×60 um^2 are implemented in the proposed infrared detector. The noise equivalent temperature difference （NETD） values are experimentally measured to be 520 and 300 mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30×30 um^2 has a potential of achieving an NETD value of 10 mK.
文摘HgCdTe多层异质结技术是未来主流红外探测器发展的重要技术方向,在高工作温度、双/多色和雪崩光电管等高性能红外探测器中扮演着重要的角色。近年来基于多层异质结构的Hg Cd Te高工作温度红外探测器得到了快速发展,尤其是以势垒阻挡型和非平衡工作P~+-π(ν)-N~+结构为主的器件受到了广泛的研究。本文系统介绍了势垒阻挡型和非平衡工作P~+-π(ν)-N~+结构HgCdTe红外探测器的暗电流抑制机理,分析了制约两种器件结构发展的关键问题,并对国内外的研究进展进行了综述。对多层异质结构Hg CdTe红外探测器的发展进行了总结与展望。
文摘As the infrared technology continues to advance, there is a growing demand for multispectral detectors for advanced IR systems with better target discrimination and identification. Both HgCdTe detectors and quantum well GaAs/AlGaAs photodetectors offer wavelength flexibility from medium wavelength to very long wavelength and multicolor capability in these regions. The main challenges facing all multicolor devices are more complicated device structtures, thicker and multilayer material growth, and more difficult device fabrication, especially when the array size gets larger and pixel size gets smaller. In the paper recent progress in development of two color HgCdTe photodiodes and quantum well infrared photodetectors is presented. More attention is devoted to HgCdTe detectors. The two color detector arrays are based upon an n P N (the capital letters mean the materials with larger bandgap energy) HgCdTe triple layer heterojunction design. Vertically stacking the two p n junctions permits incorporation of both detectros into a single pixel. Both sequential mode and simultaneous mode detectors are fabricated. The mode of detection is determined by the fabrication process of the multilayer materials. Also the performances of stacked multicolor QWIPs detectors are presented. For multicolor arrays, QWIP’s narrow band spectrum is an advantage, resulting in low spectral crosstalk. The major challenge for QWIP is developing broadband or multicolor optical coupling structures that permit efficient absorption of all required spectral bands.
基金Project supported by National Key Research and Development Program of China(Grant No.2016YFB0402402)the National Natural Science Foundation of China(Grant No.61521005)
文摘This paper presents a review of recent advances in quantum well and quantum cascade infrared photodetectors developed in Shanghai Institute of Technical Physics, Chinese Academy of Sciences(SITP/CAS). Firstly, the temperature-and bias-dependent photocurrent spectra of very long wavelength(VLW) GaAs/AlGaAs quantum well infrared photodetectors(QWIPs) are studied using spectroscopic measurements and corresponding theoretical calculations in detail. We confirm that the first excited state, which belongs to the quasi-bound state, can be converted into a quasi-continuum state induced by bias and temperature. Aided by band structure calculations, we propose a model of the double excited states that determine the working mechanism in VLW QWIPs. Secondly, we present an overview of a VLW QWIP focal plane array(FPA)with 320×256 pixels based on the bound to quasi-bound(BTQB) design. The technology of the manufacturing FPA based on the QWIP structures has been demonstrated. At the operating temperature of 45 K, the detectivity of QWIP FPA is larger than 1.4×10^(10) cm·Hz^(1/2)/W with a cutoff wavelength larger than 16 μm. Finally, to meet the needs of space applications, we proposed a new long wavelength quantum cascade detector with a broadband detection ranging from 7.6 μm to 10.4 μm. With a pair of identical coupled quantum wells separated by a thin barrier, acting as absorption regions, the relative linewidth(?E/E) of response can be dramatically broadened to 30.7%. It is shown that the spectral shape and linewidth can be tuned by the thickness of the thin barrier, while it is insensitive to the working temperature. The device can work above liquid nitrogen temperature with a peak responsivity of 63 mA/W and Johnson noise limited detectivity of 5.1×10~9 cm·Hz^(1/2)/W.
