Abrupt interfaces on InP(110): Cases of Sb and Sn

Abstract

The formation of the Sb and Sn/InP(110) interfaces has been studied in situ by soft x-ray core level photoemission spectroscopy. It is found that in both cases the growth of the first uniform monolayer is followed by the formation of large overlayer islands (Stranski–Krastanov mode). The dramatic sharpening of the substrate core levels at one monolayer of Sb indicates the formation of an ordered epitaxial overlayer. No such effect is seen for Sn for which the In 4d core level shows an indication of surface disruption. Despite the lack of order, this interface also remains mostly nonreactive. A straightforward analysis of the data for these particularly simple interfaces indicates nonequivalent shifts in the P 2p and In 4d core levels which are taken as a measure of the band bending. The origin of this discrepancy is shown to be related to an additional interface component in the In 4d core level data. The results of this study indicate that even for nonreactive InP interfaces one must take this into account in using core level photoemission data for quantitative band bending determination. Interestingly, both Sb and Sn, although nonreactive, appear to form Ohmic contacts to InP(110).