MODEL FOR THE INTERACTION OF ELECTRON WAVES WITH HETEROJUNCTIONS IN GAAS ALAS(001)/

A three-valley model of a GaAs/AlAs heterostructure has been developed by a pseudopotential method. The construction is based on results of a multiband calculation of the joining matrices J(ij) (i and j specify the valleys) at a GaAs/AlAs (001) heterojunction and the transmission coefficients of a two-barrier GaAs/AlAs(4a)/GaAs(8a)/AlAs(4a)/GaAs st ructure, where a is the lattice constant. This model correctly describ es electronic processes near the heterojunction. In this model, the mo st important elements, corresponding to the interaction of states whic h derive from the Gamma(1), X(1), and X(3) valleys of the lower conduc tion band, are incorporated in the matrix J(ij). The electron wave fun ctions in the GaAs and AlAs layers are approximated in a limited basis of states corresponding to extrema of the conduction and valence band s. Parametric expressions are derived for the matrix elements J(ij) Th ese expressions retain all features of the energy dependence of these elements contained in the exact expressions.