First-principles modeling of high-field transport in diamond

Ultra-Wide Bandgap (UWBG) semiconductors, such as diamond, represent the next generation of power electronics technology. Impact ionization properties in such materials are mediated by electron–phonon interactions, which are not well understood in such materials. In this study, we present results for impact ionization coefficients and critical field predictions in diamond from full-band Monte Carlo simulations using ab initio inputs, including electronic band structure from BerkeleyGW, phonon dispersion from Density-Functional Perturbation Theory (DFPT) in Quantum Espresso, and electron–phonon interactions from EPW. The resulting impact ionization coefficients show good agreement with experimental data available for holes and predict critical fields greater than 2 MV/cm at doping levels above 10¹⁵ cm⁻³.