Comparison of low- and room-temperature damage formation in Ar ion implanted GaN and ZnO

Ar ion implanted GaN and ZnO are studied at 295 K by Rutherford backscattering spectrometry in channelling configuration. Under these conditions in both materials damage formation proceeds in four steps which are characterised by the accumulation of point defects (I), a first saturation of the relative damage concentration at a value well below 10% (II), a second increase of the damage concentration (III) and a second plateau at about 60% for GaN and 40% for ZnO (IV). The results obtained here are compared to those reported previously for Ar ion implantation into these materials performed at 15 K. The main result of our studies is that damage formation is nearly the same for implantation at 295 K and 15 K. This suggests that thermally enhanced defect diffusion is not the main driving force during ion implantation of these materials. The shape of the channelling spectra observed in stages III and IV suggests the existence of both a high concentration of defect clusters and extended defects. The latter are proven to exist after implantation at 295 K. Therefore, there are arguments to conclude that extended defects form already during implantation at 15 K.