High-speed short-wave infrared Si-based GeSn MQW phototransistor: an alternative to existing photodetectors

Abstract

This work demonstrates high-performance vertical GeSn multiple quantum well (MQW) heterojunction phototransistors (HPTs) on Si substrates for short-wave infrared (SWIR) applications. Estimated results show a strong dependence on the number of QWs (N), incident optical power and capture parameter . Enhanced carrier and gain confinement cause an increase in responsivity of the device with the QWs in the base layer. However, the frequency performance of the device degrades with more QWs due to the increased forward transit time. On the other hand, the 3 dB cut-off frequency is the highest for the lower value of . In addition, the detectivity and responsivity of the device decrease with an increase in incident optical power due to the change in base potential. The calculated results show that the 3 dB cut-off and maximum operating frequency are and , respectively for N = 1 at 300 K. The detectivity and noise equivalent power are and , respectively for N = 3 at 300 K under 0.4 applied bias voltage. These promising results of the presented GeSn MQW HPT can pave the way for efficient low-noise high-speed photodetection applications under a low applied bias voltage.