Kinetic coefficients of semiconductor superlattices in high-frequency electromagnetic fields

Kinetic coefficients of semiconductor superlattice are obtained from the Boltzmann transport equation with Bhatnagar–Gross–Krook (BGK) collision term and Poisson equation. Using the universal analytic procedure, we found kinetic coefficient in the quasistatic limit starting from the exact solution of the Boltzmann transport equation. It is shown that the Einstein relation for the diffusion coefficient is applicable only for weak fields and it is not valid in the general case. As a consequence, a drift-diffusion model of miniband transport in the case of strong dc and ac fields should be corrected, taking into account the kinetic coefficients obtained from the Boltzmann equation.