Influence of magnetic field on electromagnetic instabilities in semiconductor superlattices.

Electromagnetic instability criteria in semiconductor superlattices (SL) in the region of a negative differential conductivity (NDC) are studied in the presence of a static transverse field. The regimes with vertical constant electric field in a "short" plate of SL and with vertical current density vector in a "long" plate are considered. The effective differential conductivity tensors for both these regimes are derived and the influence of the magnetic field on the NDC threshold and the growth increment is investigated. The frequencies of the excited waves and the dependence of the growth increment on the direction of propagation for the extraordinary waves are determined.