Optical Properties of Nano-Crystalline ZnO-AL2 O3 Thin Films

Abstract

In this study preparing elevenths samples of Zinc oxide doping by Aluminum oxide by formal (Z〖nO)〗_X 〖〖(AL〗_2 O_3)〗_(1-X) .Then study the effect of difference concentrations on the optical , electrical and morphology . Properties of Al2O3 on the ZnO thin films, prepared on glass slides by Sol-gel method .The optical characteristics of the prepared thin films have been investigated by UV-VIS spectrophotometer in the wavelength range (200 – 800) nm . The morphology characteristics of the prepared thin films have been investigated by XRD and used optical method to calculated the electrical properties. The films have a direct allow electronic transition with optical energy (Eg) the value of untreated sample (ZnO) obtained was (3.615) eV while for other untreated sample (Al2O3 )obtained was (3.511) eV .The value of( Eg) was decreased from (3.615) eV to (3.511) eV. The decreasing of (Eg) related to decreasing Aluminum Oxide index for ( Al2O3 )1-x on the samples. The maximum value of (n) is (2.13) for all samples at the difference wavelength which is agreement with (red sheft when the Aluminum Oxide index for ( Al2O3 )1-x increased for all samples of (ZnO)x (Al2O3)1- x . Dislocation density decreases and the number of unit cells increases with increasing in the calcinations (ZnO) x (Al2O3)1-x ratio that leads to increase the crystal growth and decreasing the defects in crystallites. The crystallite size increases with increasing the (Al2O3) rated. the relation between the rated of make (ZnO)x (Al2O3)1-xand d- spesing. On the other hand, it's noticed that the rated of (ZnO) increasing with decreases of the d- spesing and construction to larger clusters. Dislocation density decreases and the number of unit cells increases with increasing in the calcination (ZnO) x (Al2O3)1-x ratio that leads to increase the crystal growth and decreasing the defects in crystallites. The high magnitude of optical conductivity (1.3x1011 )Ω-1 cm-1 confirms the presence of very high photo-response of the eleven samples prepared by (ZnO)x (Al2O3)1- x form . The increased of optical conductivity at high photon energies is due to the high absorbance of eleven samples prepared by (ZnO)x (Al2O3)1- x formand may be due to electron excitation by photon energy. The results indicate the films have good characteristics for optoelectronic applications.