Low-cost self-powered shortwave infrared photodetectors with GeSn/Ge multiple quantum wells grown by magnetron sputtering

A self-powered shortwave infrared (SWIR) p-i-n photodetector (PD) is proposed and demonstrated with a Ge _0.932 Sn _0.068 /Ge multiple-quantum-wells (MQWs) active region and a p-type GeSn cap layer grown on n-type Ge (100) substrate by magnetron sputtering. The remarkable low dark current density of 19.4 mA/cm ² for the PD under -1 V bias is achieved due to the defect-free pseudomorphic GeSn/Ge MQWs and the effective surface passivation of the mesa by plasma- enhanced atomic layer deposition technique. The photoresponse spectrum extends to 2000 nm with a high peak responsivity of 0.386 A/W at 1530 nm at room temperature. The response covers atmospheric airglow spectrum and meets the need of night vision imaging applications. This work offers a pathway for the low-cost, large-scale production of SWIR PD arrays with standard complementary metal-oxide-semiconductor (CMOS) compatible technology.