Oxidation study of GaN using x-ray photoemission spectroscopy

The oxidation of GaN at room temperature was investigated using x-ray photoemission spectroscopy. The onset of oxidation is observed at 10(5) Langmuir (L=10(-6) Torr s) of oxygen exposure. This is seen both in changes in the percent composition of oxygen and in shifts in the core spectrum of Gallium. The oxidation saturates at an exposure of 10(8) L. Detailed core level analysis shows that at this exposure most of the surface Ga atoms have been oxidized. The results indicate that the oxidation of GaN is a kinetically limited process restricted to the surface and the underlying bulk is not strongly perturbed. This is in sharp contrast with GaAs where oxidation begins at the same level of exposure and then continues for all further exposures as subsurface layers are oxidized. (C) 1999 American Institute of Physics. [S0003-6951(99)03543-3].