GeSn-on-Si Avalanche Photodiodes for Short-Wave Infrared Detection

In this work, we report the growth, fabrication, and characterization of GeSn-on-Si Avalanche Photodiodes with a Sn concentration of up to 2.2%. The Ge 1-x Sn x absorption layer was grown at a very low temperature of 200°C by using molecular beam epitaxy. We show record low dark currents limited by a perimeter leakage path, only and therefore not influenced by the Sn concentration, while the absorption for a wavelength of 1,550 nm increases significantly.