Investigation on structure evolution of ion-implanted GaN epi-layers

Abstract

By employing a combination of advanced characterization techniques, including X-ray diffraction (XRD) rocking curve, Raman spectroscopy, and transmission electron microscopy (TEM), the formation and evolution of lattice defects in the GaN epitaxial layer implanted with He-alone, He first and then H, and H-alone were systematically investigated. The surface compressive stress of the annealed sample co-implanted with H/He ions was measured to be approximately 1.2 GPa by Raman spectroscopy. The changes in the full width at half maximum (FWHM) before and after annealing were also obtained by XRD. The dislocation loops and generated bubbles inside the sample were carefully observed by a high-resolution TEM. The implantation of He ions can provide more capture sites for H, form composite defects, and improve the hydrogen retention fraction. These findings advance the mechanistic understanding of ion beam slicing for GaN thin film fabrication and elucidate the evolution of lattice damage induced by ion implantation.