INVESTIGADORES
ALDAO celso Manuel
artículos
Título:
Abrupt Interfaces with Novel Structural and Electronic Properties: A Metal-Cluster Deposition and Metal-Semiconductor Junctions
Autor/es:
G.D. WADDILL; I.M. VITOMIROV; C.M. ALDAO; S.G. ANDERSON; C. CAPASSO; J.H. WEAVER
Revista:
PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS
Editorial:
APS
Referencias:
Año: 1990 vol. 41 p. 5293 - 5305
ISSN:
0163-1829
Resumen:
Abrupt interfaces with no observed substrate disruption are produced by a novel method of
metal-semiconductor junction formation. This method involves the condensation of a thin Xe
buffer layer on cleaved surfaces to isolate the semiconductor from impinging metal atoms. This Xe
buffer layer provides a surface upon which the metal atoms diffuse, nucleate, and grow into metallic
clusters. These clusters are then brought into contact with the substrate when the Xe is thermally
desorbed. The result is an abrupt, nondisrupted, nearly ideal interface. Photoemission studies of
Al, Ag, Au, Ga, Ti, and Co clusters grown on n- and p-type GaAs(110) show unique Fermi-level positions
-0.3 and 1.0 eV below the conduction-band minimum, respectively, that are nearly metal
and coverage independent. We find no evidence that metal-induced gap states or conventional defect
levels are important in determining the Fermi-level position in the gap, but photoemission results
indicate surface unrelaxation around the clusters. This unrelaxation results in the reappearance
of states in the gap. High-resolution electron-microscopy results for Au(clusters)/GaAs(110)
show intimate contact with no intermixing at the interface, with sintering of Au clusters to form an
interconnected network of metal islands at high coverages. Comparisons of these results with those
for interfaces formed by atom deposition at 60 and 300 K emphasize the novel properties of the
cluster interface.