Low noise low dark current AlAsSb/GaAsSb digital alloy avalanche photodiode

This study introduces a digital alloy AlAsSb/GaAsSb avalanche photodiode (APD) on InP, demonstrating low dark current and low noise performance. The lattice-matched AlAsSb/GaAsSb APD structure exhibits a dark current density of 16 μA/cm² at a gain of 10 and an excess noise factor near 2 at room temperature, attributed to high crystal quality and effective passivation. The dark current level achieved in this work is the lowest reported for Sb-based p-i-n APDs with a 1000 nm thick intrinsic region. These results make it highly promising for separate absorption, charge, and multiplication (SACM) structures in optical communication and LIDAR applications.