Non-local impact ionization coefficients in Al0.8Ga0.2As

Abstract

Non-local impact ionization coefficients for Al0.8Ga0.2As, essential for accurate modeling of thin avalanche photodiodes (APDs), are reported over the electric field range of 328–1500 kV cm−1. The coefficients were fitted for hard dead space non-local models such as random path length and recurrence models using previously reported photomultiplication measurements. An evolutionary algorithm was developed to aid parameter optimization. The validity of the coefficients was verified by accurately simulating the multiplication and excess noise characteristics of very thin Al0.8Ga0.2As APDs. The unique characteristics of impact ionization in such thin structures and the improved determinism in ionization locations are highlighted through modeling using the new coefficients, highlighting how the excess noise factor can be suppressed.