Black GeSn on Silicon for Enhanced Short‐Wave Infrared Detection and Imaging

Abstract Sensitive and cost‐effective group‐IV short‐wave infrared (SWIR) photodetectors (PDs), compatible with complementary metal−oxide semiconductor (CMOS) processes, are crucial for various emerging applications. Here, a black GeSn thin‐film PD on silicon, optimized for efficient SWIR photodetection and imaging is developed. Incorporating Sn into the Ge layer effectively extends the photodetection range to 1960 nm. The blackening of the GeSn surface results in a substantial reduction of reflection loss across a broad spectral range of 1200–2200 nm. Furthermore, the responsivity experienced a remarkable increase of 145% through reduced reflection loss and carrier multiplication by the carrier ionization. The black GeSn surface significantly boosts the detectivity, enhances the wide‐angle SWIR photodetection, and improves the quality of the resultant images. This demonstration heralds a new era for CMOS‐compatible, cost‐effective, high‐performance black GeSn PDs and imagers for a wide range of applications in the underexplored SWIR region.