Effect of Cr doping and photoresponse properties of photodiode based on CdO thin films

Abstract

Cadmium oxide (CdO) and chromium (Cr) doped CdO thin films with various Cr wt% contents (0.1, 0.5, 1, 2 at.%) are synthesised on soda lime glass (SLG) substrates. Results from X-ray analysis indicate that all thin films are in cubic nature with (111) preferential orientation. Cr doping does not appear to result in a transition from one crystal phase to another. CdO with the 2.0 wt% Cr doping absorbs much more light than undoped CdO in low wavelength region (< ≈450 nm), giving a maximum absorption peak in the ultraviolet region. Cr doped CdO/p-Si heterojunction shows the Cr wt% content-sensitive rectification property, achieving a high ratio of 105. In addition, Cr doped CdO/p-Si heterojunction exhibits photodiode behavior and possesses an improved photo-to-dark current ratio of ≈153. This work introduces an occasion to develop the optoelectronic devices based on Cr doped CdO thin films.