Disordering and dopant behaviour in Au+-ion- irradiated AlN

Single-crystal AlN films on SiC were irradiated at 145 K with 1.0 MeV Au+ ions in a wide range of ion fluences. The accumulation of disorder on both the Al and N sublattices in AlN has been investigated in situ using conventional Rutherford backscattering spectrometry (RBS) and non-RBS along the < 0001 >-axial channelling direction. The results suggest that a disorder saturation stage is attained following an initial disorder increase at doses less than 10 displacements per atom (dpa). A continuously amorphized layer was not formed in AlN for doses up to 208 dpa. Similar disordering behaviour is observed for the Al and N sublattices. The lattice disorder produced at 145 K is thermally stable at room temperature; further irradiation does not induce disorder recovery. The microstructures in the irradiated AlN exhibit both amorphous and crystalline domains at the stage of disorder saturation. The implanted Au does not show significant redistribution during the ion irradiation or room-temperature annealing.