The chemical vapor deposition of silicon on a patterned silicon substrate leads to the formation of 3D microcrystals, which, due to their inclined top facets and high aspect ratio, produce a light‐trapping effect enhancing the optical absorption in the near‐infrared (NIR). In this work, it is demonstrated that Si microcrystals can form the building blocks of a new class of NIR sensitive photodetectors operating in a linear or avalanche regime. Microcrystal‐based devices are designed by coupling a 2D kinetic‐growth model with a Poisson drift‐diffusion solver and fabricated by combining electron beam lithography and low‐energy plasma‐enhanced chemical vapor deposition (LEPECVD). The optoelectronic properties of microcrystal‐based p–i–n photodiodes are investigated both theoretically and experimentally by means of finite‐difference time‐domain (FDTD) simulations and responsivity measurements. At 1000 nm wavelength, the responsivity of microcrystal‐based devices is six times higher than that of an equivalent mesa diode. Moreover, the photocurrent gains of Si microcrystals operating as an avalanche photodiode (APD), at the same wavelength, reaches 2 × 104 demonstrating the potentialities of substrate patterning, combined with epitaxial growth, for amplified photodetection applications.

中文翻译：

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硅外延微晶中的近红外光捕获和雪崩倍增

硅在图案化硅基板上的化学气相沉积导致 3D 微晶体的形成，由于其倾斜的顶面和高纵横比，产生光捕获效应，增强近红外 (NIR) 的光学吸收。在这项工作中，证明硅微晶可以形成以线性或雪崩状态运行的新型近红外敏感光电探测器的构建块。基于微晶的器件是通过将二维动力学生长模型与泊松漂移扩散求解器耦合来设计的，并通过结合电子束光刻和低能等离子体增强化学气相沉积（LEPECVD）来制造。微晶材料的光电特性p–我–n通过时域有限差分 (FDTD) 模拟和响应率测量对光电二极管进行了理论和实验研究。在 1000 nm 波长下，基于微晶的器件的响应度比同等台面二极管高六倍。此外，硅微晶作为雪崩光电二极管（APD）在相同波长下的光电流增益达到2×104展示了基板图案化与外延生长相结合用于放大光电检测应用的潜力。