Post-deposition annealing effects of copper oxide (Cu2O) thin film deposited using E-beam evaporation

In this work, a thin copper (I) oxide (Cu2O) layer was deposited on p-type silicon substrates using the E-beam evaporation method without using any catalyst. The fabricated copper oxide sample was annealed at different annealing temperatures ranging from 300 to 700 degrees C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to examine the structural and morphological analysis of the as-deposited and annealed samples. The XRD results reveal the phase transition of the copper (II) oxide (CuO) sample and the presence of CuO was also confirmed by peaks at similar to 35.79 degrees and similar to 38.94 degrees, which correspond to (11 - 1) and (220) crystal planes, respectively. A semi-cubic-shaped rough surface was observed from the top view SEM image after annealing at 600 degrees C for 1 h. Also, surface composition was evaluated by the X-ray photoelectron spectroscopy which strongly indicates the formation of Cu2O in the as-deposited sample, which changes to the CuO phase after annealing at 600 degrees C. Further, the absorbance spectra show absorption enhancement in the IR region after annealing of the Cu2O thin films . Moreover, it was found that the optical bandgap of the as-deposited sample decreases from similar to 2.17 to similar to 1.43 eV after annealing. Therefore, this process of developing high quality copper oxide-TF deposited on Si substrate using the E-beam evaporation technique can be used to develop a variety of opto-electronic applications.