Structural order in oxygenated gallium nitride films

Structural order in nanocrystalline, oxygenated GaN thin films (thickness ~ 500 nm) has been examined. The films were grown using low-pressure chemical vapor deposition of (CH₃)₂GaN₃ single source precursor. During deposition, residual oxygen from the vacuum environment was incorporated into the films. Photoemission spectroscopy indicated that oxygen mainly substituted nitrogen during deposition. Long-range X-ray diffraction indicated that the films were oriented along the hexagonal (002) direction when the incorporated concentration of oxygen was lower than 25 atomic % (at. %). Above this, the films were amorphous. The results of angle-dependent near-edge X-ray absorption fine structure facilitated the formation of a short-range structural model, which explained the influences of the oxygen concentration on the long-range order in the films. These studies are useful in understanding the structural evolution in doped-nitride films.