Influence of High Energy Radiation on the Structural Properties of Gallium Nitride Films

Gallium Nitride (GaN) thin films were fabricated via the molecular beam epitaxy (MBE) technique. A plasma source with a radio frequency (rf) plasma source was used --as the nitrogen source. A conventional effusion cell was used to provide Ga flux. The samples used in this study were grown on two substrates types: on Si less than111greater than substrates and sapphire less than0001greater than substrates. The used samples were exposed to three different gamma doses (?) of 1600 kGy, 3700 kGy, 5300 kGy using Cobalt-60 source. The effect of gamma radiation on the structural properties of GaN films has been systematically studied via a computer-aided X-ray diffractometer. The results confirm that the first, second and third dose of gamma caused shifting in 2? towards the lower side, and that shifting increase with an increase in the radiation dose in the GaN film. The FWHM was widened and reduced the intensity ratio (IA/IB) by increasing the gamma radiation dose from 1600 kGy to 3700 kGy and 5300 kGy. The effect of the thin film thickness and the N/Ga ratio on the structural properties of ?Film quality? was also investigated before and after ? -radiation. The results show a decrease in the film quality after exposing the film to films to ?-radiation. This decrease in film quality may be due to creating crystal defects and disorders in the crystal lattice. These defects and disorders increased with increasing the dose of ?-radiation.