Germanium (Ge)-based photodetectors have become one of the mainstream components in photonic-integrated circuits (PICs). Many emerging PIC applications require the photodetectors to have high detectivity and low power consumption. Herein, we demonstrate high-detectivity Ge vertical p-i-n photodiodes on an in-situ heavily arsenic (As)-doped Ge-on-Si platform. The As doping was incorporated during the initial Ge-on-Si seed layer growth. The grown film exhibits an insignificant up-diffusion of the As dopants. The design results in a ∼45× reduction on the dark current and consequently a ∼5× enhancement on the specific detectivity (D*) at low reverse bias. The improvements are mainly attributed to the improved epi-Ge crystal quality and the narrowing of the device junction depletion width. Furthermore, a significant deviation on the AsH₃ flow finds a negligible effect on the D* enhancement. This unconventional but low-cost approach provides an alternative solution for future high-detectivity and low-power photodiodes in PICs. This method can be extended to the use of other n-type dopants (e.g., phosphorus (P) and antimony (Sb)) as well as to the design of other types of photodiodes (e.g., waveguide-integrated).

中文翻译：

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Ge-on-Si籽晶层生长过程中原位重质As掺杂的低功率和高检测率Ge光电二极管

基于锗（Ge）的光电探测器已经成为光子集成电路（PIC）的主流组件之一。许多新兴的PIC应用要求光电检测器具有高检测率和低功耗。本文中，我们演示了在原位重掺杂砷（As）的Ge-on-Si平台上的高探测Ge垂直p - i - n光电二极管。在最初的Ge-on-Si种子层生长过程中掺入了As掺杂。生长的薄膜显示出微不足道的As掺杂剂向上扩散。该设计使暗电流降低了约45倍，因此比检测率提高了约5倍（D*）在低反向偏置下。改善主要归因于改善的Epi-Ge晶体质量和器件结耗尽宽度的缩小。此外，AsH ₃流量的显着偏差对D *增强的影响可忽略不计。这种非常规但低成本的方法为PIC中未来的高探测性和低功耗光电二极管提供了替代解决方案。该方法可以扩展到使用其他n型掺杂剂（例如，磷（P）和锑（Sb））以及设计其他类型的光电二极管（例如，集成波导）。