Comprehensive simulation study of CMOS-compatible GeSn nBn photodetectors for e-SWIR technology

Ge1−xSnx photodetectors (PDs) have emerged as a promising class of CMOS-compatible detectors for infrared (IR) and a wide range of applications, including sensing, healthcare, and space technology. In this study, we present a comprehensive theoretical simulation of GeSn/SiGeSn nBn PDs, using GeSn as the absorber material, to assess their potential in advancing IR detection technology. Our theoretical model solves the Poisson and continuity equations, evaluating key parameters such as energy band variation, carrier distribution, electric field characteristics, electrostatic potential variation, and dark current behavior. The results indicate that while the dark current density increases with higher Sn composition, variations in the Si composition of the barrier layer have a negligible impact on the diffusion-limited dark current density. Furthermore, the increased tunneling distance and restricted carrier injection into the absorber limit excess carrier accumulation, thereby reducing contributions from Auger1 and radiative recombination. In addition, the longer transit path increases the chance of carrier recombination before contributing to the dark current. These combined effects result in a substantial decrease in dark current density. Our findings underscore the potential of GeSn-based PDs as effective components for scalable and Si-compatible extended-short-wave infrared (e-SWIR) technologies.