Jm. Woodall et al., THE CONTINUING DRAMA OF THE SEMICONDUCTOR INTERFACE, Philosophical transactions-Royal Society of London. Physical sciences and engineering, 344(1673), 1993, pp. 521-532
Studies on III-V compound semiconductor surfaces and metal interfaces
are discussed. For GaAs and InP surfaces aqueous photowashing or chalc
ogenide coatings can significantly reduce surface state densities. For
metal interfaces experimental conditions have been found which lead t
o metal work function dominated Schottky barrier heights to GaAs. Fina
lly, using special epilayer samples of GaAs, AlGaAs and InGaAs contain
ing a significant excess of As, more has been learned about the origin
of the invariance of the interface Fermi level (pinning) commonly obs
erved at III-V semiconductor interfaces. The excess As can form either
a high density of point defects or a dispersion of elemental As clust
ers depending on the post growth annealing conditions. It has been fou
nd that the pinning effects of point defects are qualitatively differe
nt from those due to the clusters of elemental As. Specifically, when
the excess As is in the form of As precipitates, the As forms a Schott
ky barrier whose barrier height is well characterized by the parameter
s of As work function and semiconductor electron affinity.