Preparation and Characterization of Ag/CuO/n-Si/Ag Heterojunction Diode by Sol–Gel DIP-Coating Technique

This study focused on the fabrication of copper oxide (CuO) thin films using the sol-gel dip-coating technique, with precursor molar concentrations of 0.3 and 0.75 M, to create Ag/CuO/n-Si/Ag heterojunction diodes. The electrical characterization was performed in both dark conditions and under illumination (100 to 200 mW/cm²) to examine the effects of precursor concentration on device performance. Key electrical parameters, including saturation current, barrier height, ideality factor, series resistance, and rectification ratio, were extracted from the current–voltage (I–V) characteristics using thermionic emission theory and Cheung’s method. Additionally, the forward bias I–V characteristics were analyzed with the space charge limited current (SCLC) model to identify the dominant conduction mechanisms. The ideality factors decreased from 3.83 to 2.9 for our samples as the molar concentration increased. Nonetheless, the barrier height was observed to rise with an increase in molar concentration, measuring 0.6 eV for 0.3 M and 0.61 eV for 0.75 M molar concentration, respectively. Atomic force microscopy (AFM) results showed that higher concentrations of precursors led to smoother surfaces with a decrease in roughness from 26.47 to 18.96 nm and also led to a decrease in grain sizes from 32.53 to 15.73 nm, which are often correlated with improved electrical performance. Overall, the findings of this study provide valuable insights into the relationship between precursor concentration, morphological features, and electrical characteristics of heterojunction diodes, contributing to the optimization of design and fabrication processes for enhanced performance in various optoelectronic applications.