High‐Performance N‐MoSe2/P‐GeSn/N‐Ge van der Waals Heterojunction Phototransistor for Short‐Wave Infrared Photodetection
Xinwei Cai, Shuo Li, Jinhui Qian, Haokun Ding, Songsong Wu, Rui Wang, Qiang Wu, Xiaowei Shentu, Guangyang Lin, Cheng Li- Atomic and Molecular Physics, and Optics
- Electronic, Optical and Magnetic Materials
Abstract
In this work, a high‐performance two‐terminal n‐MoSe2/p‐GeSn/n‐Ge van der Waals (vdW) heterojunction phototransistor (HPT) is proposed and demonstrated for short‐wave infrared (SWIR) detection. With a high Sn content of 17.1% in the GeSn base region, the cutoff wavelength is extended to beyond 2400 nm. The substantial electron/hole injection ratio resulting from the large bandgap offset between the MoSe2 emitter and the GeSn base enables the harvesting of high photocurrent gain. A record high responsivity of 12.75 A W−1 and an excellent specific detectivity of 1.74 × 1010 Jones at 2250 nm are achieved under a collector‐emitter bias of 1.0 V at room temperature. A response time of 462 µs at 1550 nm outbalancing that of most vdW junction‐based devices is obtained for the non‐optimized devices. Those results show that the mixed‐dimensional GeSn HPT is one of the promising candidates for detection of infrared band above 2 µm.