Effect of pre-existing disorder on surface amorphization in GaN

Single crystal GaN epilayers with pre-existing surface disordered layers are bombarded at room temperature with 40 and 100 keV P ions. Stable lattice defects are studied by Rutherford backscattering/channeling spectrometry. Results show that the rate of planar surface amorphization is independent of the concentration of pre-existing defects near the amorphous/crystalline (a/c) interface. In contrast, the formation of stable defects in the crystal bulk in the vicinity of an a/c interface is influenced by the presence of the interface. These experimental observations suggest that the a/c interface, as compared to stable bulk damage, is a more efficient sink for mobile point defects with respect to both processes of point defect recombination and trapping. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3462380]