High performance silicon-based GeSn p-i-n photodetectors for short-wave infrared application

An investigation of germanium-tin (GeSn) on silicon p-i-n photodetectors with a high-quality Ge_0.94Sn_0.06 absorbing layer is reported. The GeSn photodetector reached a responsivity as high as 0.45 A/W at the wavelength of 1550 nm and 0.12 A/W at the wavelength of 2 μm. A cycle annealing technology was applied to improve the quality of the epitaxial layer during the growth process by molecular beam epitaxy. A low dark-current density under 1 V reverse bias about 0.078 A/cm² was achieved at room temperature. Furthermore, the GeSn photodetector could detect a wide spectrum region and the cutoff wavelength reached to about 2.3 μm. This work has great importance in silicon-based short-wave infrared detection.