Free surfaces and multilayer interfaces in the GaAs/AlAs system

Semiempirical potential energy functions have been utilized for a variety of calculations in the Ga-Al-As system. Surface energies have been calculated for several orientations of GaAs. Ledge energies for the GaAs (0 0 -1) (As-terminated) surface show long-range interaction effects with the ledge energy increasing with spacing. GaAs (001)/AlAs (001) superlattices have been simulated for a range of interlayer spacings with the excess interfacial energy per interlayer increasing from 5 erg/sq cm at an interlayer spacing of 1 molecular layer (5.8 A) to 50 erg/sq cm at an interlayer spacing of 18 molecular layers (103.8 A).