Ge-on-Si SPADs for Quantum Communications

单光子探测器在量子通信、量子光学和光子量子信息处理等一系列量子技术应用中是必不可少的。与传统的p-i-n和线性雪崩光电探测器(APD)相比，它们还可以为一系列应用提供显著的好处，包括测距、光检测和测距(LiDAR)、面部识别和隐蔽成像分析。CMOS单光子雪崩二极管(SPAD)已经商业化多年，但硅的带隙限制了波长超过约1微米的光的工作。在硅雪崩区域添加锗吸收剂使SPAD能够在电信所需的较长波长下运行，这为LiDAR提供了巨大的好处，因为系统可以在存在遮蔽和降水的情况下以更高的精度运行。此外，Ge-on-Si SPAD有可能比目前可用的商业技术便宜200多倍，这意味着这一领域的研究正受到世界各地主要汽车制造商和电信公司的兴趣。为该项目提出的研究将继续发展格拉斯哥半导体设备集团正在进行的工作，提供一种新的Ge-on-Si SPAD器件设计，该器件可以很容易地耦合到用于量子密钥分发和量子通信测试系统的光纤。格拉斯哥大学的半导体设备集团是此类设备的全球先驱，在短波红外波长的这种基于硅的技术方面处于显著领先地位，展示了第一批Ge-on-Si SPAD光电探测器和最近打破纪录的单光子探测效率(SPDE)。能够复制这种水平的探测效率并提高其他关键的优点系数(FOM)，如后脉冲、抖动和噪声等效功率(NEP)，将是产生适用于量子系统的新设计的关键。这项工作将包括设计设备，在詹姆斯·瓦特纳米制造中心接受制造设备的培训，以及使用电子和光学技术对设备进行表征，以确定其性能。会议将与学术界的顶尖研究人员以及英国量子通信中心和英国工业的合作者进行接触，以了解最终用户的性能要求，并在真实系统中测试成功开发的设备。

Single-photon detectors are essential for a range of quantum technology applications such as quantum communications, quantum optics and photonic quantum information processing applications. They can also provide significant benefit com- pared to conventional p-i-n and linear avalanche photodetectors (APDs) for a range of applications including range-finding, Light Detection and Ranging (LiDAR), facial recognition and covert imaging analysis. CMOS Single Photon Avalanche Diodes (SPADs) have been commercially available for many years, but the band gap of silicon limits operation using light beyond approximately 1 um in wavelength. Adding germanium absorbers onto silicon avalanche regions allows SPADs to operate at the longer wavelengths required for telecommunications and which provides significant benefits for LiDAR as systems can operate with greater accuracy in the presence of obscurance and precipitation. Further to this, Ge-on-Si SPADs have the potential to be over 200 times cheaper than the present commercial technologies available, meaning that this area of research is receiving interest from major automotive manufacturers and telecommunication companies from around the world. The research proposed for this project will continue to develop work being undertaken at the Semiconductor Devices Group at Glasgow by delivering a new design of Ge-on-Si SPAD devices which can be easily coupled to optical fibres for use in quantum key distribution and quantum communication test systems. The Semiconductor Devices Group at the University of Glasgow is the global pioneer of such devices and has a significant lead in this silicon-based technology at short wave infrared wavelengths, demonstrating the first Ge-on-Si SPAD photodetectors and more recently record-breaking single photon detection efficiencies (SPDE). Being able to replicate this level of detection efficiency and improve other key Figures of Merit (FOMs) such as afterpulsing, jitter and Noise Equivalent Power (NEP) will be crucial to producing a new design that is suitable for use in quantum systems. The work will include designing devices, being trained to fabricate devices in the James Watt Nanofabrication Centre and the characterisation of the devices using electronic and optical techniques to determine their performance. There will be engagement with top researchers in academia and collaborators in the UK Quantum Communications Hub and UK industry to understand the end user performance requirements as well as to test successfully developed devices in real systems.