STRUCTURAL, ELECTRICAL, AND OPTICAL PROPERTIES OF GERMANIUM-DOPED ZnO THIN FILMS DEPOSITED BY PULSED LASER DEPOSITION TECHNIQUE

Abstract

ABSTRACT Germanium-doped ZnO thin films (0.1 at.%) were deposited at various temperatures by using pulsed laser deposition technique. An x-ray diffractometer was used to investigate the structural properties of the thin films. All of the thin films had preferred (002) and (004) orientations, and the peak intensity of the (004) orientation increased with increasing growth temperature. An Atomic force microscope was used to investigate the surface morphologies of the thin films. The grain size and the surface roughness of the thin film increased with growth temperature. A spectrophotometer was used to measure the transmittances of the thin films. The band gap energies of the thin films were calculated by linear fitting the sharp absorption edge of high-quality thin films. A spectrometer was used to investigate the luminescent properties of the thin films. It was observed that the intensity of near band edge emission increased with increasing temperature and no deep-level emission was observed. Hall measurements indicated that all the thin films were n-type semiconductors, and the thin films grown at high temperatures showed the lower resistivity and the higher mobility.