Core-level photoemission and near-edge x-ray absorption fine-structure studies of GaN surface under low-energy ion bombardment

The compositional changes on GaN surfaces under the low energy Ar ion bombardment were analyzed. The bombarded surfaces were characterized using synchrotron-based high-resolution core-level photoemission measurements and near-edge x-ray absorption fine-structure (NEXAFS) spectroscopy. The uncoordinated Ga nad N atoms at the surface were formed due to the impact of energetic Ar ions which break the Ga-N bond on the GaN surface. It was observed that the low-energy ion bombardment of GaN had produced Ga-rich surface layer that transformed into a metallic Ga layer at higher bombarding energies. The results show that the NEXAFS and core-level photoemission are used to identify the point defects in the near-surfaces region by ion bombardment.