Thick Al_(0.85)Ga_(0.15)As_(0.56)Sb_(0.44) avalanche photodiodes on InP substrates

摘要

We present gain, dark current and excess noise characteristics of PIN Al_(0.85)Ga_(0.15)As_(0.56)Sb_(0.44) (hereafter AlGaAsSb) avalanche photodiodes (APDs)on InP substrates with 1000 nm thick multiplier layers. The AlGaAsSb APDs were grown by molecular beam epitaxy using a digital alloy technique(DA) to avoid phase separation. Current-voltage measurements give a peak gain of ～42, a breakdown voltage of-54.3 V, and a dark current density at a gain of 10 of ～145 μA/cm~2. Excess noise measurements of multiple AlGaAsSb APDs show that k (the ratio of electron and hole impact ionization coefficients) is ～0.01. This k-value is comparable to Si, which is widely used for visible and near-infrared APDs. The low dark current density and low excess noise suggest that such thick AlGaAsSb layers are promising multipliers in separate absorption, charge and multiplication (SACM) structures for short-wavelength infrared applications such as optical communication and LIDAR, particularly on a commercial InP platform.