High‐Performance N‐MoSe2/P‐GeSn/N‐Ge van der Waals Heterojunction Phototransistor for Short‐Wave Infrared Photodetection

• Published in: Advanced optical materials 2024-02, Vol.12 (5), p.n/a
• Main Authors: Cai, Xinwei, Li, Shuo, Qian, Jinhui, Ding, Haokun, Wu, Songsong, Wang, Rui, Wu, Qiang, Shentu, Xiaowei, Lin, Guangyang, Li, Cheng
• Format: Article
• Language: English
• Subjects: Cut off wavelength; Emitters; heterojunction phototransistor; Heterojunctions; Intermetallic compounds; Molybdenum compounds; Photoelectric effect; Room temperature; short‐wave infrared photodetection; Tin; van der Waals heterojunction
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202301724

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. A two‐terminal n‐MoSe2/p‐GeSn/n‐Ge mixed‐dimensional van der Waals heterojunction phototransistor is demonstrated for short‐wave infrared broadband photodetection from 800 to 2400 nm. Sputtering‐grown GeSn renders an extension of the detection range beyond 2400 nm. The large bandgap offset between MoSe2 and GeSn provides a huge carrier injection ratio, resulting in record‐high responsivity and detectivity at 2250 nm.