The effect of solvent on the structural, morphological, optical and electrical properties of spray pyrolysed boron doped CdO thin films

Abstract

In this communication, the influence of solvent (water and mixed solvent) on the structural, surface microstructural, dc-electrical and optical properties of spray deposited cadmium oxide (CdO) thin films doped with different weight percentages (wt%) of boron (B) on microscopic glass substrates at 300 °C is reported. The X-ray diffraction (XRD) analysis suggests that the samples are polycrystalline in nature and the crystallinity is enhanced by B doping concentrations. The average crystallite size of (200) plane is ranging 29–90 and 40–138 nm for water, and mixed solvent of water and methanol (1:1), respectively. Oxidation state of B doped CdO thin film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The surface microstructures of B doped CdO thin films are effectively modified by solvent and the average particle size varies between 301 and 466 nm for water solvent and 221 and 705 nm for mixed solvent used B doped CdO films. The direct optical band gap energy values varies between 2.11 and 2.35 eV for water and 2.43 and 2.54 eV for mixed solvent used B doped CdO thin films. High average transmittance (80 %) and high mobility of 64.42 cm2 /V s were obtained for 1.0 wt% B doped CdO thin film deposited using mixed solvent. The mixed solvent used 1.0 wt% B doped CdO thin film has high figure of merit (16.2 × 10−3 Ω−1). The variations in electrical resistivity, carrier concentration, mobility and optical transmittance with respect to spray solvents have been discussed.