Short wavelength infrared avalanche photodetector using Sb-based strained layer superlattice

We demonstrate a low noise short wavelength infrared (SWIR) Sb based type II superlattice (T2SL) avalanche photodiodes (APD). The SWIR GaSb/(AlAsSb/GaSb) APD structure was designed based on impact ionization engineering and grown by molecular beam epitaxy on GaSb substrate. At room temperature, the device exhibits a 50 % cut-off wavelength of 1.74 micron. The device revealed to have electron dominated avalanching mechanism with a gain value of 48 at room temperature. The electron and hole impact ionization coefficients were calculated and compared to give better prospect of the performance of the device. Low excess noise, as characterized by the carrier ionization ratio of ~ 0.07, has been achieved.