Characterization of octahedral Cu2O nanostructures grown on porous silicon by electrochemical deposition

Abstract

Cuprous oxide (Cu2O) nanostructures on porous silicon (PSi) were obtained by an electrochemical deposition method. The effects of current density and deposition time on structural, optical and I–V characteristics of PSi/Cu2O nanostructures were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) methods, diffuse reflectance spectra and current-voltage (I–V) measurements. SEM analysis revealed that the shape of Cu2O nanostructures was mostly truncated octahedral and pyramid, and their size increased with increasing deposition time and current density. From XRD analysis, it was found that Cu2O nanostructures were polycrystalline, cubic phase and their preferential orientation was along the [111] direction. In addition, it was found that with increasing current density, the average crystallite size of Cu2O nanostructures decreased, whereas FWHM, micro deformation and dislocation values increased. The diffuse reflectance spectra indicated that the average reflectivity of PSi/Cu2O samples obtained in 30 and 60 min deposition times are about 19%. The current-voltage (I–V) measurements of PSi/Cu2O samples at room temperature (300 K) and in the dark environment revealed that samples exhibited rectifier properties and behaved like a typical p-n junction diode. In addition, it was found that the I–V parameters obtained from thermionic emission and Cheung's model are found to depend on the deposition time and current density. The PSi/Cu2O sample prepared at 0.5 mA/cm2 for 60 min had the smallest ideality factor and series resistance among all samples. The values of ideality factor and barrier height were determined using the conventional thermionic emission (TE) model and Cheung's model and the obtained results have been compared with each other.