Effect of Al2O3 decoration on the opto-electrical properties of a porous Si/Cr2O3 composite

Abstract

In this work, we present an extensive investigation of the effect of Al₂O₃ decoration on the morphological, structural and opto-electronic properties of a porous Si (Sip)/Cr₂O₃ composite. The Sip layers were prepared by the anodization method. Al₂O₃ and Cr₂O₃ thin films were deposited by physical vapour deposition. The morphological and micro-structural properties of Sip/Cr₂O₃/Al₂O₃ were studied using the scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction techniques. It was found that Al₂O₃ decoration with different concentration strongly affects the Sip/Cr₂O₃ microstructure mainly at the level of porosity. Variable angle spectroscopic ellipsometry demonstrates a strong correlation between optical constants (n and k) of Sip/Cr₂O₃/Al₂O₃ and microstructure properties. Dielectric properties of Sip/Cr₂O₃/Al₂O₃ such as electrical conductivity and conduction mechanism were explored using impedance spectroscopy over the temperature interval ranging from 340 to 410°C. A semiconductor to the metallic transition has been observed at high frequency