Thermal annealing of InN films grown by metal-organic chemical vapor deposition

Indium nitride films, grown at 375 °C by low-pressure metal-organic chemical vapor deposition, have been annealed at temperatures ranging from 400 °C to 475 °C under an ambient ammonia atmosphere. According to our X-ray diffraction spectra of the annealed InN films, the integrated intensity of the InN (0002) diffraction peak reaches its minimum value at the temperature of 425 °C, but the full-width at half maximum of the InN (0002) peak shows an opposite change with the annealing temperature. These results indicate that the InN film annealed at 425 °C has the worst structural quality. Scanning electron microscope and X-ray photoelectron spectroscope measurements demonstrate that as the annealing temperature is increased to 425 °C, the density of indium grains on the surface increases greatly due to the volatilization of nitrogen atoms. Above 425 °C, the density of the indium grains begins to decrease, resulting from the desorption of indium. The indium grains formed during this annealing process are then supposed to be responsible for the degraded structural quality in the annealed InN.