MONTE-CARLO ANALYSIS OF BAND-STRUCTURE INFLUENCE ON IMPACT IONIZATION IN INP

The influence of electronic band structure on the impact ionization phenomena in InP was studied using the Monte Carlo method. Realistic band structures evaluated using the nonlocal pseudopotential method were employed. Threshold energies for impact ionization were calculated throughout the first Brillouin zone. A new impact ionization model which explicitly takes into account the wave-vector dependence of impact ionization threshold energies was used to calculate the ionization rate. The simulation results of drift velocity and ionization coefficient agree very well with experimental data. In spite of significant anisotropy in the threshold energies and complex band structures, no significant orientational dependence was found in the ionization coefficients. An important result of the work presented here is the demonstration that the biaxial elastic strain in InP produced by the lattice mismatch between adjacent layers in a heterostructure can significantly alter the impact ionization thresholds.