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Here, we report the effect of the substrate, sonication process, and postannealing on the structural, morphological, and optical properties of ZnO thin films grown in the presence of isopropyl alcohol (IPA) at temperature 30–65 °C by the successive ionic layer adsorption and reaction (SILAR) method on both soda lime glass (SLG) and Cu foil. The X-ray diffraction (XRD) patterns confirmed the preferential growth thin films along (002) and (101) planes of the wurtzite ZnO structure when deposited on SLG and Cu foil substrates, respectively. Both XRD and Raman spectra confirmed the ZnO and Cu-oxide phases of the deposited films. The scanning electron microscopy image of the deposited films shows compact and uniformly distributed grains for samples grown without sonication while using IPA at temperatures 50 and 65 °C. The postannealing treatment improves the crystallinity of the films, further evident by XRD and transmission and reflection results. The estimated optical band gaps are in the range of 3.37–3.48 eV for the as-grown samples. Our experimental results revealed that high-quality ZnO thin films could be grown without sonication using an IPA dispersant at 50 °C, which is much lower than the reported results using the SILAR method. This study suggests that in the presence of IPA, the SLG substrate results in better c-axis-oriented ZnO thin films than that of deionized water, ethylene glycol, and propylene glycol at the optimum temperature of 50 °C. Air annealing of the samples grown on Cu foils induced the formation of Cu x O/ZnO junctions, which is evident from the characteristic I–V curve including the structural and optical data.

Cuprous oxide (Cu2O) thin films have been grown on both soda lime glass (SLG) microscope slides and Fluorine-doped Tin Oxide (FTO) substrates by a modified SILAR technique. The pH level of the bath solution was systematically varied in the range of 4.50 – 7.95 to elucidate their effect on the physical properties of the deposited product. The prepared films showed compact surface morphology composed of spherical grains evident from their SEM images. The XRD measurement showed that the as-deposited films were single phase Cu2O with (111) preferred orientation and this texturing was found to be increasing with increasing pH and annealing temperature. The annealed Cu2O films were found to be stable up to 200 °C and completely converted to cupric oxide (CuO) phases when the temperature reached to 350 °C. The estimated optical bandgaps of the as-grown samples were found in the range of 2.28 – 2.48 eV using UV-Vis-NIR transmission data and showing a bandgap narrowing trend with the decreasing level of solution pH. The effect of post-annealing temperatures (75-350 0C) on the as-deposited films was also studied and found to be crucial to control the optical bandgap (1.44 – 2.13) eV and electrical properties of the films. The sheet resistance of the as-deposited samples was found to be decreasing from 4120 MΩ/square to 800 MΩ/square while grown with increasing acetic acid content in the precursor solutions and decreasing up to 2.66 MΩ/square while annealing up to 250 °C in the air.

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Cuprous oxide (Cu 2 O) nanorods have been deposited on soda-lime glass substrates by the modified successive ionic layer adsorption and reaction technique by varying the concentration of NaCl electrolyte into the precursor complex solution. The structural, electrical and optical properties of synthesized Cu 2 O nanorod films have been studied by a variety of characterization tools. Structural analyses by X-ray diffraction confirmed the polycrystalline Cu 2 O phase with (111) preferential growth. Raman scattering spectroscopic measurements conducted at room temperature also showed characteristic peaks of the pure Cu 2 O phase. The surface resistivity of the Cu 2 O nanorod films decreased from 15 142 to 685 Ω.cm with the addition of NaCl from 0 to 4 mmol and then exhibited an opposite trend with further addition of NaCl. The optical bandgap of the synthesized Cu 2 O nanorod films was observed as 1.88–2.36 eV, while the temperature-dependent activation energies of the Cu 2 O films were measured as about 0.14–0.21 eV. Scanning electron microscope morphologies demonstrated Cu 2 O nanorods as well as closely packed spherical grains with the alteration of NaCl concentration. The Cu 2 O phase of nanorods was found stable up to 230°C corroborating the optical bandgap results of the same. The film fabricated in presence of 4 mmol of NaCl showed the lowest resistivity and activation energy as well as comparatively uniform nanorod morphology. Our studies demonstrate that the nominal presence of NaCl electrolytes in the precursor solutions has a significant impact on the physical properties of Cu 2 O nanorod films which could be beneficial in optoelectronic research.