Avalanche photodiode featuring Germanium-tin multiple quantum wells on silicon: Extending photodetection to wavelengths of 2 and beyond

We report the first demonstration of a Ge_0.9Sn_0.1 multiple quantum wells on Si avalanche photodiode (Ge_0.9Sn_0.1 MQW/Si APD), achieving a cutoff wavelength λ above 2 μm. This is a major milestone as APDs with cutoff wavelength above 2 μm is traditionally achieved using III-V materials. The peak avalanche gain of the APD is observed to be dependent on incident light power Pin and wavelength λ. A high optical responsivity of 0.33 A/W is achieved at λ = 2003 nm due to the internal avalanche multiplication.