Evaluation of ambipolar diffusion coefficient in AlxGa1−xN semiconductor

Abstract

Numerical approach to account for the influence of randomly fluctuating potential on carrier mobility in compound semiconductors with compositional disorder is developed and exploited for calculating the heavy hole-defined ambipolar diffusion coefficient in AlxGa1-xN layers. The rates of inelastic heavy hole-phonon scattering were obtained by integrating the quasi-classical hole-phonon scattering rates for the virtual crystal over the semiclassical confining potential obtained by using the local landscape method. The calculated dependence of the heavy-hole diffusion coefficient on the aluminum content in AlxGa1-xN crystal in a wide compositional range (x = 0 – 1) evidences a substantial influence of localization on the diffusivity of nonequilibrium carriers and is in a good quantitative correspondence with the experimental data obtained in this work by using the light-induced transient grating technique. The adopted Monte Carlo simulation technique also enables diffusivity calculations in other multicomponent compounds (e.g., high-In-content InGaN) and their structures, in particular, those for LEDs and µ-LEDs.