INDIRECT ADATOM INTERACTIONS VIA III-V SEMICONDUCTOR SUBSTRATES

Substrate-mediated interactions between adatoms on III-V semiconductor s are investigated by using the self-consistent Anderson-Newns model i n the Hartree-Fock approximation. The Green function formalism of the Dyson equation approach is employed to derive Chebyshev polynomial exp ressions for the chemisorption energy, interaction energy, and charge transfer, in terms of the adatom separation d. An alternating s- and p -orbital model of GaSb and InAs enabled interacting hydrogen adatoms o n their (100) and (111) faces to be studied. As in the metal-substrate case, the chemisorption energy decreased with increasing band widths and adbond energy and, additionally, with increasing band gap. The int eraction energy was found to have a d(-2) damping factor for the (100) faces and a d(-3) factor for the (111) faces, its magnitude being lar ger for smaller gaps. Self-consistency is shown to play a significant role in interaction energy calculations for small values of d. In the case of charge transfer, its variation with d is purely a self-consist ent result. (C) 1998 John Wiley & Sons, Inc.