Surface Morphology and Opto-electronic Properties of Nanostructured Cr doped CdO Thin Films for Photovoltaics

Abstract

CdO thin films doped with different concentrations of chromium were deposited on mica substrates by DC reactive magnetron sputtering method. The effect of Cr concentration (1% to 5%) on structural, electrical and optical properties of CdO films was investigated. The structural studies reveal that the films are polycrystalline with preferred orientation along (1 1 1) plane. From the FESEM micrographs, it was clearly seen that all the films have smooth and homogeneous surface morphology. The optical transmittance of 72% and minimum resistivity of 5.36 x 10-4Ω.cm is obtained for 4% Cr doped CdO thin films. The optical band gap of Cr doped CdO thin films increases from 2.72 to 2.81 eV with the increase of Cr concentration due to Burstein-Moss effect. The optical constants such as absorption coefficient (α), extinction coefficient (k) and refractive index (n) were determined from the optical transmission data.