Effect of Thickness on the Structural, Electrical and Optical Properties of ZnO Films Deposited by MBE

Abstract

A set of ZnO films of different thickness have been deposited on sapphire substrates using molecular beam epitaxy (MBE) by varying the growth time and the effect of film thickness on the structural, electrical and optical properties have been investigated. The X-ray diffraction (XRD) results indicate that the full width at half maximum (FWHM) of the (002) diffraction peak is decreased as the film thickness increasing, and the stress along c-axis is stable. Scanning electron microscope (SEM) measurement shows that the grains become more uniform as the film grows thicker and the film surface present distinct hexagon shape as the film is grown up to a thickness of 500nm. The optical absorbance, Hall mobility and photoluminescence (PL) intensity are increased in accordance with the thickness of the film.