HIGH-FIELD MINIBAND CONDUCTION IN GAAS/ALAS SUPERLATTICES

The present communication is focussed on the velocity-field characteristics in a superlattice (SL) miniband as a function of the superlattice parameters and the temperature, in relation with experimental results on a series of GaAs/AlAs superlattices. The Boltzmann transport equation is numerically solved in taking into account both electron-phonon and interface roughness scattering. Meanwhile the model confirms that the peak velocity only weakly depends on the scattering frequency, the large dispersion in criticial field values are well accounted for by interface scattering with a monolayer fluctuation length of the order of 30-50 angstrom, and which depends on the well thickness prior to other parameters. We also discuss the apparent discrepancy observed between theoretical and experimental variation of the upsilon(F) laws with the lattice temperature.