Cu sputtered Cu/ZnO Schottky diodes on fluorine doped tin oxide substrate for optoelectronic applications

Abstract

In the present work, ZnO thin films were deposited on fluorine doped tin oxide (FTO) and soda lime glass substrates using sol-gel spin coating technique. Cu thin films were deposited on ZnO by the sputtering technique through a shadow mask for the Schottky diode application. The effect of solution concentration on the structural, morphological, optical and electrical properties of the deposited thin films were investigated. X-ray diffraction pattern shows that all thin films have a wurtzite structure with (002) orientation. Scanning electron micrographs revealed concentration dependent surface morphology. The transmittance of thin films were measured in the wavelength range 300 nm–800 nm and it was found that the optical bandgap decreased from 3.28 eV to 3.21 eV as molarity increased. For optoelectronic applications of the thin film samples, the current-voltage (I-V) measurements were performed for optimizing molar concentrations. The electronic parameters of the Cu/ZnO schottky diode such as ideality factor (η) and barrier height (Φ B ) were obtained using I-V curve. The highest stauration current was obtained 8.67 × 10 −4 A for 0.5 M thin film sample at 5 V bias voltage. The obtained results indicate that the electrical properties of the Cu/ZnO Schottky diodes can be tuned by molar concentrations.