Germanium-Tin on Silicon avalanche photodiode for short-wave infrared imaging

The first demonstration of Germanium-Tin on Silicon (Ge_1-xSn_x/Si) avalanche photodiode (APD) for short-wave infrared (SWIR) imaging is reported. The temperature dependence of breakdown voltage was characterized. An extracted thermal coefficient of 0.05% K^-1 indicates that the Ge_1-xSn_x/Si APD achieved a lower thermal sensitivity than conventional III-V-based APDs. At the wavelength λ of 1600 to 1630 nm, a responsivity of ~ 1 A/W (bias voltage V_bias = -9.7 V) was achieved due to the internal avalanche gain of Ge_1-xSn_x/Si/Si APD. The monolithic and CMOS-compatible Ge_1-xSn_x/Si APD presented here shows promise in SWIR imaging applications where low-cost and high sensitivity sensing arrays are needed.