Dopant Concentration Dependences and Symmetric Fermi Level Movement for n- and p-GaAs(110) Interfaces Formed at 60K,

C.M. ALDAO; S.G. ANDERSON; C. CAPASSO; G.D. WADDILL; I.M. VITOMIROV; J.H. WEAVER

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

APS

Año: 1989 vol. 39 p. 12977 - 12980

0163-1829

The coverage-dependent Fermi-level movement for Ag, Co, and Ti interfaces formed at 60 K on n-type and p-type GaAs is shown to be symmetric but dependent on the bulk dopant concentration. Photoemission results show that EF remains close to the band edges until ?1 monolayer for doping of 1 & 10´ cm while EF movement is induced by far fewer adatoms for doping of 2X10´ cm with overshooting for p-type GaAs. Remarkable surface chemical and structural insensitivity is reAected by similar band-bending trends for adatoms which exhibit very diA´erent reactivities and amounts of substrate disruption. We conclude that EF movement is controlled by the coupling between adatom-induced states and those of the substrate at low temperature, with strong dependence on the bulk doping of the semiconductor.