Ion-assisted deposition of amorphous GaN: Raman and optical properties

We report the preparation of amorphous GaN by ion-assisted deposition and studies of the Raman and optical response of the resulting films. The films are transparent across the visible and show an edge whose energy and structure are in close agreement with crystalline material, suggesting a low density of gap states and homopolar bonds. The Raman spectrum is similar to a broadened vibrational density of modes calculated for wurtzite GaN, with a Raman cross section which varies among the vibrational bands.