Conductivity of a superlattice during electron scattering by optical phonons

The conductivity is calculated for a semiconductor with a superlattice with simultaneous actions of constant (E) and varying (E_o cos t) electric fields, considered quasiclassically. It is shown that in calculating the current-voltage characteristics (CVC) at low temperatures (k_oT h _o, _o being the optical phonon frequency) and e_o = 0 it is necessary to consider electrons as both absorbing and nonabsorbing optical phonons. The frequently used approximation of constant relaxation time is valid only for k_oTh_o, when scattering by optical phonons dominantes.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 81–84, January, 1982.