INVESTIGADORES
ALDAO celso Manuel
artículos
Título:
Temperature Effects for Ti/GaAs(110): Interface Formation Involving Cluster and Atom Deposition
Autor/es:
C.M. ALDAO; G.D. WADDILL; S.G. ANDERSON; J.H. WEAVER
Revista:
PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS
Editorial:
APS
Referencias:
Año: 1989 vol. 40 p. 2932 - 2939
ISSN:
0163-1829
Resumen:
Ti/GaAs(110) interfaces formed at 60 and 300 K by atom-by-atom deposition and by the deposition
of preformed metallic clusters exhibit very different Schottky-barrier behavior and morphologies.
For atom deposition, temperature-dependent Fermi-level pinning is similar to that observed
for nonreactive metals, despite the fact that the deposition process leads to the disruption of ?3
monolayers of GaAs at all temperatures. Although disruption is apparent even at 0.02 A, atom
deposition at 60 K on n-type GaAs shows almost no Fermi-level movement until -2 A when EF
moves rapidly toward midgap. Our results show that the adatoms do not act as nonreactive donors
at low temperature, that thermal changes do not quench surface chemistry, and that surface reaction
alone does not lead to midgap pinning. In contrast, for interfaces formed by preformed Ti cluster
deposition, unique pinning positions are observed far from the point expected for known defects
or metal-induced gap states. The instability of the Ti(cluster)/GaAs system is demonstrated by
warming to 300 K. We postulate that kinetically restricted reactions occur beneath the metallic
clusters and the midgap pinning requires disruption in the presence of a metallic overlayer.