Structural, Surface Morphological and Optical Properties of Cr Doped CdO Thin Films for Optoelectronic Devices

Abstract

Cr doped CdO thin films have been deposited on glass substrates with various concentrations of Cr (1%, 2%, 3%, 4% and 5%) by DC reactive magnetron sputtering method. XRD studies reveal that the films exhibit polycrystalline with preferred orientation along the (2 0 0) plane. AFM images of the thin films have a surface topography with nanosized grains and dispersed well on the surface without any cracks. The resistivity decreases from 6.83 x 10-4 to l.83 x 10-4Ω.cm with the increase of Cr concentration from 1 to 3% then it increases to 3.83 x 10-4Ω.cm with the increase of Cr concentration to 5%. The optical band gap of Cr doped CdO thin films increases from 2.55 to 2.85eV with increase of Cr concentration due to Burstein-Moss effect. The best figure of merit of 4.56x10-2Ω-1 is obtained for 3% Cr doped CdO thin film with a low resistivity of 1.83 x 10-4Ω.cm, optical transmittance of 86% and low sheet resistance of 5.2Ω/sq.