近日，芬兰阿尔托大学电子与纳米工程系的Hele Savin及其研究团队取得一项新进展。他们研制出了具有>1A/W响应度的近红外锗PIN光电二极管。相关研究成果已于2025年1月1日在国际知名学术期刊《光：科学与应用》上发表。

本文展示了一种采用CMOS兼容锗（Ge）材料纳米工程制造的PIN光电二极管，该二极管在室温、零偏压条件下，在1.2～1.6微米的宽波长范围内实现了超过90%的实测外部量子效率（EQE）。例如，在1.55微米波长处，其响应度达到1.15安培/瓦。除了在近红外（NIR）波段表现出优异的光谱响应外，该器件在可见光和紫外波段的性能也保持高水平（EQE在300纳米以下甚至超过100%），从而实现了异常宽的光谱响应范围。

这一高性能是通过使用表面纳米结构减少光学损失，以及采用共形原子层沉积氧化铝表面钝化和基于介电诱导电场的载流子收集（而非传统pn结）来减少电学损失而实现的。在5伏反向偏压下测得的暗电流密度为76微安/平方厘米，低于以往报道的锗光电二极管。这些研究成果将对锗光电二极管的设计与制造以及近红外检测领域产生即时影响。

据悉，尽管高效近红外（NIR）检测对众多应用至关重要，但目前的NIR检测器要么在检测入射光子方面能力有限，即光谱响应率较差，要么采用昂贵的III-V族非CMOS兼容材料制成。

附：英文原文

Title: Near-infrared germanium PIN-photodiodes with >1A/W responsivity

Author: Liu, Hanchen, Pasanen, Toni P., Fung, Tsun Hang, Isomets, Joonas, Haarahiltunen, Antti, Hesse, Steven, Werner, Lutz, Vhnissi, Ville, Savin, Hele

Issue&Volume: 2025-01-01

Abstract: Even though efficient near-infrared (NIR) detection is critical for numerous applications, state-of-the-art NIR detectors either suffer from limited capability of detecting incoming photons, i.e., have poor spectral responsivity, or are made of expensive group III-V non-CMOS compatible materials. Here we present a nanoengineered PIN-photodiode made of CMOS-compatible germanium (Ge) that achieves a verified external quantum efficiency (EQE) above 90% over a wide wavelength range (1.2–1.6μm) at zero bias voltage at room temperature. For instance, at 1.55μm, this corresponds to a responsivity of 1.15A/W. In addition to the excellent spectral responsivity at NIR, the performance at visible and ultraviolet wavelengths remains high (EQE exceeds even 100% below 300nm) resulting in an exceptionally wide spectral response range. The high performance is achieved by minimizing optical losses using surface nanostructures and electrical losses using both conformal atomic-layer-deposited aluminum oxide surface passivation and dielectric induced electric field -based carrier collection instead of conventional pn-junction. The dark current density of 76μA/cm² measured at a reverse bias of 5V is lower than previously reported for Ge photodiodes. The presented results should have an immediate impact on the design and manufacturing of Ge photodiodes and NIR detection in general.

DOI: 10.1038/s41377-024-01670-4

Source: https://www.nature.com/articles/s41377-024-01670-4