Structural, electrical and optical characterization of Mn doped CdO photodiodes

Abstract

Undoped CdO, 0.2% Mn doped CdO, 6% Mn doped CdO and 10% Mn doped CdO photodiodes were prepared using sol-gel method and deposited on Si substrate at room temperature. Electrical and optical properties of the diodes were assessed, and surface properties were investigated using atomic force microscopy. Atomic force microscopy assessment revealed that undoped and Mn doped CdO thin films were formed in a granular structure where grains composing thin film spread homogeneously on a substrate. To assess the electrical properties current - voltage (I - V), current – time (I - t) graphs were obtained in various illumination intensities; it was seen that diodes show rectifying properties and good photovoltaic behaviour. Photo-characterizations revealed that photodiodes show increasing photocurrent with increasing illumination intensities; the photodiodes also show decreasing capacitance with increasing frequency. Optical properties of the thin films were assessed using UV–vis spectrometry. Bandgap energies were calculated using UV–vis absorption spectra which were found between 2.41 eV and 1.70 eV.