High-responsivity GeSn short-wave infrared p-i-n photodetectors

Surface-illuminated GeSn p-i-n photodetectors (PDs) with Ge0.964Sn0.036 active layer on Ge substrate were fabricated. Photodetection up to 1.95 mu m is achieved with a responsivity of 0.13 A/W. High responsivities of 0.56 and 0.71 A/W were achieved under a reverse bias voltage of 3V at 1640 and 1790 nm, respectively. A low dark current of 1.08 mu A was obtained at a reverse bias of 1V with a diameter of 150 mu m, which corresponds to a current density of 6.1mA/cm(2). This value is among the lowest dark current densities reported among GeSn PDs. (C) 2013 AIP Publishing LLC