Envelope functions for conduction-electron states at GaAs(110)

Low-lying conduction band wave functions are calculated for semi-infinite G aAs(110), using the layer-Korringa-Kohn-Rostoker method. It is found that t he envelope functions for the orbitals with even mirror symmetry are in qua drature with the envelopes for the odd orbitals. The even orbitals dominate , and a single envelope function with a node close to the surface works wel l. The tunneling into the surface barrier is rather constant for the stares considered, within 0.28 eV of the bottom of the conduction band. Thus rece nt scanning tunneling microscopy experiments on subsurface impurity screeni ngs in accumulation layers with this amount of band-bending probe the surfa ce charge density.