Binding-energy shifts from alloying at metal–compound-semiconductor interfaces

One can relate the binding energy of a metal core level in a binary alloy as measured by photoemission to partial heats of solution. This principle is applied to explain the high-coverage behavior of cation core levels at metal–compound-semiconductor interfaces where alloying between the overlayer metal and the cation species is suspected or known to occur. Calculated and measured binding energies are compared for a wide range of noble and transition metals on GaAs and InP. Close agreement in many systems shows that alloying at these interfaces is more general than previously recognized. Implications of these results on previous interpretations of data will be discussed for specific interfaces. Limitations of the model and the extent of its applicability to other metal-semiconductor interface systems will also be outlined.