Near infrared single photon detection using Ge-on-Si heterostructures

随着新的应用领域的出现，如量子信息处理，特别是量子密码学，基于半导体的光子计数探测器在过去十年中崛起。这些主要由硅制成的光子计数探测器还在许多实验室应用中取代了光电倍增管，在这些应用中，它们的室温操作、快速计时、占地面积小和低功耗已被证明在许多应用中具有优势，例如荧光寿命成像。近年来，在地面、机载甚至卫星上的激光诱导反射技术(例如用于检测痕量气体浓度)以及在低功率光学成像和高分辨率深度成像方面的重大发展，已经发展了新的光子计数应用领域。在近红外光谱区域--硅基探测器的效率非常低--现有的单光子雪崩二极管(SPAD)探测器仍然存在重大问题。由于相对较窄的带隙上载流子的热激发产生的高噪声水平，以及间隙中间陷阱中心的影响导致后脉冲的有害影响，从而进一步导致探测器噪声水平，它们的性能恶化。该项目旨在建立一类新的锗/硅SPAD，它将在近红外，特别是在具有战略重要性的电信波段高效运行，并将低噪声硅单光子雪崩倍增的优势与GE的红外传感能力相结合。这种新型探测器将利用外延Ge/Si生长方面的最新进展，并与最近成立的英国硅光子学联盟(UKSP)一起制造，该联盟提供世界级的器件生长和制造设施。探测器将在现有的最先进的量子密钥分发和飞行时间测距/深度成像试验台上进行验证。该项目利用现有英国Silicon Photonics财团的综合专业知识和设施来进行额外和新的工作，从而为该财团增加价值。

Semiconductor-based photon-counting detectors have risen to prominence in the last decade as new application areas have emerged, such as quantum information processing, and in particular quantum cryptography. These photon-counting detectors - mainly fabricated from silicon - have also taken over from photomultipliers in a number of laboratory applications where their room temperature operation, fast timing, small footprint and low power consumption have proved advantageous in a host of applications, for example fluorescence lifetime imaging. New photon-counting applications areas in ground-based, airborne and even satellite-borne laser-induced reflection techniques have been developed in recent years (eg for detection of trace gas concentrations), as well as significant developments in low-power optical imaging and high-resolution depth imaging. In the near-infrared spectral region - where silicon-based detectors are highly inefficient - there remain substantial issues with available single-photon avalanche diode (SPAD) detectors. Their performance deteriorates due to the high noise levels associated with thermal excitation of carriers across the relatively narrow bandgaps, as well as the effects of mid-gap trapping centres causing the deleterious effects of afterpulsing, further contributing to detector noise levels. This project aims to establish a new class of germanium/silicon SPADs that will operate efficiently in the near-infrared, particularly at the strategically important telecommunications wavebands, and combine the advantages of low-noise Si single-photon avalanche multiplication with the infra-red sensing capability of Ge. This new class of detectors will take advantage of recent advances in epitaxial Ge/Si growth and be fabricated in conjunction with the recently-created UK Silicon Photonics consortium (UKSP), which offers world-class device growth and fabrication facilities. The detectors will be validated on existing state-of-the-art testbeds for quantum key distribution and time-of-flight ranging/depth imaging. The project leverages the combined expertise and facilities of existing UK Silicon Photonics consortium to do additional and new work, thus adding value to that consortium.