Cu IONS IRRADIATION IMPACT ON STRUCTURAL AND OPTICAL PROPERTIES OF GaN THIN FILM

Abstract

Epitaxial grown Gallium nitride ( GaN ) thin film on sapphire was irradiated with Cu ions at various fluences (5×1014, 1 ×1015 and 5×1015 cm -2). The level of lattice disorder, as measured by Rutherford backscattering spectrometry and channeling (RBS/C), gradually increases with the increasing of ions fluence. Lattice amorphization is observed for the sample irradiated with fluence of 5×1015 cm -2 which is also confirmed by X-ray diffractometer (XRD) analysis. It was found that both Raman modes of GaN layer clearly shifted with Cu + fluences. Both Raman and X-ray analyses explore that Cu atom substituted into Ga sites. Atomic force microscopy (AFM) images show the irradiated GaN surface roughness increases with the increasing ions fluence. The UV-visible transmittance spectrum and ellipsometric measurements show a decrease in the band gap value after irradiation of Cu ions in the GaN film. Moreover, the optical constants (n and k) of the films vary with the increasing of Cu ion fluences.

Introductory Chapter: Ion Beam Applications

“…Similarly, phase transformation of thin film and nanostructured materials by ion beams is another important application. Ion beam-induced controlled modification of physical properties is possible in thin film and nanostructured materials [2][3][4][5][6][7][8]. Phase segregation and separation is another unique application of ion beam [9].…”