The interface between a thin Au film deposited on an atomically clean GaN s
urface has been investigated by means of synchrotron radiation scanning pho
toelectron microscopy. The first stages of the interface formation at room
temperature and the evolution of the interface after stepwise annealing up
to 870 degreesC have been studied. Our results reveal the temperature depen
dence of the Schottky barrier heights, caused by structural rearrangements
below 500 degreesC, and by the formation of an Au gallium alloy above 500 d
egreesC. The effect of the reaction-induced heterogeneity of the interface
on the local Schottky barriers is examined.