Differences in the impurity ionization in quasi-classically strong constant and alternating electric fields in a two-dimensional superlattice based on graphene

The absorption coefficient of an electromagnetic wave in a two-dimensional graphene-based superlattice in the presence of a constant electric field for the case of quasiclassically strong electric fields is investigated. Anisotropy of the absorption coefficient was found for different orientations of the constant vector voltage and the polarization vector of alternating electric fields. It is shown that a slow increase in the absorption coefficient at low frequencies is due to impurity absorption, and it's more rapid growth at high frequencies is determined by intermini-bands transitions. These features can be used to create radiation detectors.