The Correlation between Soda’s Concentration Variation and Annealing Temperatures, Physical and Electrochemical Properties of Oxide Copper Thin Films Processed by Chemical Immersion

In this work, we have studied basically, the effect of the variation of the NaOH soda concentration, the influence of annealing temperature variation on the structural, morphological and electrochemical properties of copper oxide obtained by chemical immersion. Initially, we have obtained the nanostructures of copper oxide by chemical immersion into the electrolytes at room temperature with different concentration of NaOH: C1 (2.5 M) and C2 (0.9 M) followed by heat treatments at various temperatures. The main results were obtained by following technics X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) coupled with an energy-dispersive spectroscopy (EDS) analyzer, this study have shown that the decrease of NaOH concentration decreases the necessary temperature to obtain the Cu2O oxide. The increase of annealing temperature for the two studied electrolytes C1 and C2 influences the crystallinity of obtained layers as well as their microstructures. The current density responses revealed good dark current density values under the most basic conditions. The best value (58.24 mA/cm2) found from the nanostructures which obtained after immersion in the electrolyte C1 followed by treatment at 650°C for 1 h (58.24 mA/cm2) is due to the good crystallinity and to the crystallite size obtained after this annealing (DCuO = 34.08 nm and $${{D}_{{{\text{C}}{{{\text{u}}}_{{\text{2}}}}{\text{O}}}}}$$ = 31.04 nm). The good result of current density has also obtained from the samples immersed in C1 then annealed at 180°C for 1 h (43.76 mA/cm2) and at 250°C for 1 h (37.87 mA/cm2) where the CuO layer is solely appeared after these annealing.