Impact ionisation in Al_(0.9)Ga_(0.1)As_(0.08)Sb_(0.92) for Sb-based avalanche photodiodes

摘要

We report the impact ionisation coefficients of the quaternary alloy Al_(0.9)Ga_(0.1)As_(0.08)Sb_(0.92) lattice matched to GaSb substrates within the field range of 150 to 550 kV cm~(-1) using p-i-n and n-i-p diodes of various intrinsic thicknesses. The coefficients were found with an evolutionary fitting algorithm using a non-local recurrence based multiplication model and a variable electric field profile. These coefficients indicate that an avalanche photodiode not only can be designed to be a function in the mid-wave infrared but also can be operated at lower voltages. This is due to the high magnitude of the impact ionisation coefficients at relatively low fields compared to other III-V materials typically used in avalanche multiplication regions.