Au/GaN interface: Initial stages of formation and temperature-induced effects

Synchrotron radiation photoemission spectromicroscopy has been used to study the properties of an Au/GaN interface starting from an atomically clean GaN surface. The effects of Au coverage and temperature were examined. The results have demonstrated that annealing alters the height of the Schottky barrier, formed after deposition of a 4-monolayer (ML) Au film at room temperature. The photoemission spectra indicate that these barrier changes should be attributed to structural rearrangements of the Au film and to formation of a Au gallide interfacial layer, a product of the reaction between the Au and GaN above 500 degreesC. The photoemission images have revealed that spatial heterogeneity in the composition is developed at temperatures above 750 degreesC. The large spread of the Au/GaN barrier heights reported in the literature was discussed considering the current theoretical concepts.