INDIUM INTERACTION WITH GAP(110) - EXAMPLE OF AN UNREACTED INTERFACE

The interaction of thin layers of indium with cleaved GaP (110) surfaces was studied by high resolution core and valence level photoelectron spectroscopy using synchrotron radiation. The effects of substrate temperature on interface formation were also investigated. Since the Ga 3d and In 4d core levels have very similar binding energies, we have used the strong cross-section decrease of the In 4d level near the Cooper minimum in order to distinguish shifted Ga 3d lines at higher In depositions. While a cation exchange reaction such as observed for aluminium on III-V semiconductor surfaces is ruled out on the basis of our data, a shifted Ga 3d line of low intensity was detected; the dependence of its intensity on deposition temperature implies that this line is related to an InGa interface bond. The InGaP (110) system therefore represents an example of an unreacted interface. Detailed analysis of the In, Ga and P core level line intensities imply clustering of the adlayer at room temperature,which is strongly inhibited at low temperature. © 1990.