GAMMA-X MIXING EFFECT IN GAAS ALAS SUPERLATTICES AND HETEROJUNCTIONS

The -X mixing effect on the subband structure of superlattice (GaAs)12/(AlAs)12 is investigated with both the pseudopotential method and the effective-mass method. The results derived from the two methods show reasonable agreement, and the best-fitting -X scattering parameter t is determined to be 0.5. The transmission probabilities of the -point electron through the bound X-point states in the AlAs layer are calculated quantitatively. It is found that the resonant peaks correspond completely to the eigenstates of the corresponding superlattice, and the -resonant peak is relatively smaller than the X-resonant peaks. Under the applied electric field, the resonant peaks originating from two barriers separate, resulting in a reduction of the peak-to-valley ratio. © 1990 The American Physical Society.