Fabrication and characterization of CuO/CdS heterostructure for optoelectronic applications

Abstract

This paper reports the fabrication of a CuO/CdS heterostructure and the characterization of its properties for optical sensing. Cadmium sulfide (CdS) and cupric oxide (CuO) films were deposited by spray pyrolysis and hydrothermal techniques in order to fabricate CuO/CdS heterojunction devices. The structural, morphological, and optical properties of the CuO and CdS thin films were analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. The concentration of the sulfur precursor, thiourea, was varied over a range from 0.01 to 0.06 M in the spray coating solution for CdS films, and 0.05 M was found to yield improved structural and optical properties. The prepared p-CuO/n-CdS heterojunction exhibited good optical sensing properties with excellent response and recovery speeds. A possible photosensing mechanism for the fabricated heterostructure is detailed using energy band diagrams. In addition, heterojunction properties, including the ideality factor and conduction mechanism are reported: a fabricated heterostructure diode showed a threshold voltage of 0.036 V and an ideality factor of 1.86.