Structural disorder in ion-implanted AlxGa1−xN

The accumulation of structural damage in ${\mathrm{Al}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N}$ films (with $\text{x=0.05–0.60)}$ under heavy-ion bombardment at room temperature is studied by a combination of Rutherford backscattering/channeling spectrometry and cross-sectional transmission electron microscopy (XTEM). Results show that an increase in Al concentration strongly enhances dynamic annealing processes in AlGaN and suppresses ion-beam-induced amorphization. All AlGaN wafers studied show damage saturation in the bulk for high ion doses. Interestingly, the disorder level in the saturation regime is essentially independent of Al content. In contrast to the case of GaN, no preferential surface disordering is observed in AlGaN during heavy-ion bombardment. XTEM reveals similar implantation-produced defect structures in both GaN and AlGaN.