Mid-wavelength Infrared Avalanche Photodetector with AlAsSb/GaSb Superlattice

This work demonstrates a mid-wavelength infrared separate absorption and multiplication avalanche photodiode (SAM-APD) with AlGaAsSb/GaSb multi-quantum well as the multiplication layer and InAsSb bulk material as the absorption layer. The InAsSb-based SAM-APD structure was grown by molecular beam epitaxy. The device exhibits a 100 % cut-off wavelength of ~5.3 µm at 150 K and ~5.6 µm at 200 K. At 150 K and 200 K, the responsivity of the SAM-APD reaches a peak value of 2.26 A/W and 3.84 A/W at 4.0 µm under -1.0 V applied bias, respectively. The SAM-APD device was designed to have electron dominated avalanching mechanism via the multi-quantum well structure as the avalanche architecture. A multiplication gain value of 29 at 200 K was achieved under −14.7 V bias voltage. The electron and hole impact ionization coefficients were calculated and compared. A carrier ionization ratio of ~0.097 was achieved at 200 K.