Improved thermal stability of GaN{0001} surfaces by adsorbed C₆₀ molecules

Adsorption and desorption of C₆₀ molecules on GaN{0001}-1×1 surfaces as well as the surface decomposition by heating were investigated with Auger electron spectroscopy. The first monolayer of C₆₀ forms strong chemical bonds to the substrate atoms. A seven-step annealing procedure at temperatures up to 1275 K is presented which completely removes the adsorbed carbon without decomposing the surface. If the process is applied to clean, uncovered GaN{0001}-1×1 surfaces thermal etching with a significant Ga atom loss is observed. The results indicate that adsorbed C₆₀ increases the thermal stability of the surfaces considerably and that thermal etching begins at defects or steps at the surface where the molecules are most strongly bound. © 2000 American Institute of Physics.