A Study of High Quality Al-doped ZnO Thin Films Grown at Low Temperature by Pulsed Laser Deposition

摘要

Highly conducting and transparent Al-doped ZnO (AZO) thin films, which are oriented along c-axis and have wurtzite structure, were grown on quartz substrate at low temperature by pulsed laser deposition. The techniques of x-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), optical transmission spectroscopy (OTS), electrical resistivity, and Hall Effect were used to study the effect of growth temperature and oxygen pressure on the structural, electrical transport, and optical properties of these films. The optical transparency in all the films is high and does not change much with oxygen pressure and growth temperature. However, electrical parameters such as resistivity, carrier concentration, and mobility strongly depend on both oxygen pressure and growth temperature. The temperature dependence resistivity measurement indicates semiconducting behavior of all the films. A detailed study indicates that the films which are highly conducting and transparent correspond to an optimum temperature of 200 °C and an oxygen pressure of 5 × 10~(-7) bar. Higher transmittance of the AZO films compared with pure ZnO and ITO and comparable mobility make us to suggest that Al-doped ZnO is an excellent material for optoelectronic applications.