PNNL

Abstract

Epitaxial single-crystal gallium nitride (GaN) films on sapphire were irradiated at low and room temperatures using O? ions over a range of fluences. The accumulation of disorder on the Ga sublattice has been investigated based on He? Rutherford backscattering analysis along the -axial channeling direction. The degree of disorder in the O? irradiated GaN increases at low doses and saturates above 10 displacements per atom (dpa). The microstructures of two O?-irradiated specimens are characterized using high-resolution transmission electron microscopy. Similar planar defect structures at the saturated disorder level are observed for as-irradiated and thermally annealed GaN. The growth and annihilation of these defects during ion irradiation and thermal annealing are believed to contribute to the saturation and stability of defect concentrations.