短波红外单光子探测器的发展(特邀)

InP/InGaAs短波红外单光子探测器(SPAD)是目前制备技术较为成熟且获得广泛应用的单光子探测器，通过半导体热电制冷(TEC)即可达到的工作温度(-40℃左右)，具有体积小、成本低，方便安装和携带的应用优势；另外，基于常规半导体二极管的芯片制造工艺很容易实现大面阵单光子阵列，除了探测信号，还具备三维数字成像功能。国外包括美国、瑞士、意大利、韩国、日本等对InP/InGaAs SPAD进行了长期持续的研究，目前已研制出单管的货架产品，性能还在不断的优化和改进之中，其单光子探测器阵列呈现了清晰的三维成像效果，正在逐步应用。国内包括重庆光电技术研究所、中国科学院上海技术物理所、西南技术物理研究所、中国科学技术大学、云南大学等对InP/InGaAs SPAD芯片先后进行了器件设计和器件制备研究，目前单管的性能已经达到与国外报道相当的性能。国内单光子探测器阵列的研究获得了一定的进展，但芯片规模和器件性能有待提升。文中对国内外InP/InGaAs短波红外单光子探测器的发展，在设计和研制中存在的问题，以及近10年来的优化改进进行了介绍，重点介绍了高温、高速以及单光子焦平面阵列的发展，并结合新颖...

Advancement of shortwave infrared single-photon detectors (invited)

  Signifacance   InP/InGaAs shortwave infrared single-photon avalanche diodes (SPADs) have proved to be the most practical tool for the detection of near-infrared single-photon because of their small volume, near-room-temperature operation, and ease of integration and fabrication of a focal plane array based on the conventional semiconductor manufacturing process. They have achieved wide application including quantum secure communication, spectrum analysis, weak signal detection, Light Detection and Ranging (LiDAR), as well as self-driving vehicles considering the eye-safe laser requirement. etc. The further mass application depends on the performance and price of the SPADs, so the issues about the avalanche diode design and processing, as well as the solution are very important for accelerating the practical application. The review and analyses about the advancement of the shortwave infrared SPDs is very essential for both the academic research and application.  Progress   The separate absorption, grading, charge, and multiplication (SAGCM) structure has been used for InP/InGaAs SPADs since it was designed. This ensures the low electrical field in InGaAs absorption layer and high field in multiplication layer, then tunnelling current arising from high electrical field in absorption layer is remarkably suppressed, so the dark counts. Except for the essential material structure design, the electrical field uniformity in the multiplication layer also influences the performance such as the dark counts of the SPADs. The afterpulsing problem is another issue limiting the maximum count rate of the SPD in the current period. Focusing these issues of InP/InGaAs SPADs, solutions for them are concluded from the long-term study of InP/InGaAs SPADs.The high detection efficiency SPADs, room-temperature SPADs, and high count rate SPADs reported in the past decade by various institutions at home and abroad are summarized in detail. The typical performance parameter detection efficiency is improved by increasing the quantum efficiency via integrated absorption enhancement structure, the reported maximum value for 1 550 nm is 60%. The room temperature operation SPADs was carried out by both decreasing dark counts and sine-wave gated-quenching technology. About 20% detection efficiency and kHz dark counts at 293 K are acceptable for the practical application. Besides, the especial promising result for the room temperature SPDs is the reduced afterpulsing owing to the shortened carrier lifetime under the high temperature. The GHz SPDs benefit from the high and narrow sine-wave gate, as well as the simple harmonic wave noise out of the sine-wave gated-quenching technology. The typical performance parameter of high detection efficiency, room-temperature and high count rate InP/InGaAs SPDs are shown (Tab.1-Tab.3).Moreover, the InP/InGaAs SPAD focal plane arrays (FPAs) and the performance are concluded (Tab.4). The issues for the SPAD FPAs are mainly optical and electrical crosstalk between the adjacent pixels, solution such as mesa separation, microlens and optical filter, etc. are applied for decreasing the crosstalk. The clear three-dimensional image coded distance information was presented (Fig.13). The three-dimensional imaging with high sensitivity and long-distance detection ability attracts the enormous application requirement in both military and civil field. Finally, this paper introduces the novel SPDs technology including addition ionization engineering to the SPADs multiplication layer or using InAlAsSb digital alloys materials to further improve the performance. In_0.52Al_0.48As with smaller noise factor, wider band gap and matching the InGaAs lattice of the absorbing layer is used as the multiplication layer for electron ionization. Multiple layer ionization is applied to SPADs for increasing the ionization rate and detection efficiency.  Conclusions and Prospects   During the last decade the InP-based shortwave infrared single-photon detectors (SPDs) has gained the dramatic progress, the typical detection efficiency of the InP/InGaAs SPADs has been increased from 20% to 30%, and the dark count rate has been reduced to less than kHz. The high temperature SPADs up to room temperature operation, high speed SPADs up to GHz has appeared owing to the improvement of both avalanche diode and quench circuit. The single-photon focal plane arrays of 256×64 have also presented the clear three-dimensional image.The foreign countries including the United States, Switzerland, Italy, South Korea and Japan, etc. have performed long-term research on InP/InGaAs SPADs, and developed commercial self-products. Domestic research groups have successively prepared InP/InGaAs SPAD chips, and the performance is comparable to foreign reports. Furthermore, single-photon detector arrays have made certain progress, but the device format and performance need to be improved. Novel SPDs technology such as low noise factor material and ionization engineering are expected to further improve the performance. The high performance and low cost shortwave SPDs will further facilitate the quantity application including weak signal detection, LiDAR and digital imaging etc.