Electron and Hole Transport in Bulk ZnO: A Full Band Monte Carlo Study

Electron and hole transport in wurtzite phase ZnO is studied using an ensemble full band Monte Carlo method. The model includes an accurate description of the electronic structure obtained with the nonlocal pseudopotential method and numerically calculated impact ionization transition rates based on a wavevector-dependent dielectric function. Results of transport simulations at both low and high electric fields are presented. It is found that the low field electron mobility is close to 300 cm2 V−1 s−1 at room temperature, and the peak electron drift velocity is 2.2 × 107 cm/s at a field of 275 kV/cm. The determination of the ionization coefficients is affected by some uncertainties due to the incomplete knowledge of the high energy phonon scattering rates. Nevertheless, the present calculations of the ionization coefficients provide a reasonably accurate estimate of the impact ionization process.