Numerical fitting of Ionization coefficients for APDs based on ternary materials

The efficiency of the avalanche process in Avalanche photodiodes depends on the Ionization coefficients. Ionization coefficients are dependent on the band-structure of materials. Ionization coefficients at different temperatures and fields are predicted by an analytical formula proposed by Okuto and Crowell. In this work, we propose two different mean free paths in two different field regions. These mean free paths, taken as the fitting parameters, have been optimized at different temperatures for In
_x
Ga
_1-x
Sb (x=0.06, 0.10, 0.12, 0.18), Al
_x
Ga
_1-x
Sb (x=0.05, 0.10) and In
_x
Ga
_1-x
As (x=0.02) using Particle Swarm Optimization algorithm. The present values have been compared with previous values extracted from the formula proposed and significant improvements have been achieved.