A Study on the ZnO/CuO Nano-Diode Multilayer and Some of its Physical Properties

Abstract

Research on nanomaterials has become increasingly popular because of their unique physical, chemical, optical and catalytic properties compared to their bulk counterparts. Therefore, many efforts have been made to synthesize multidimensional nanostructures for new and efficient nanodevices. Among those materials, zinc oxide (ZnO), has gained substantial attention owing to many outstanding properties. ZnO besides its wide band gap of 3.34 eV exhibits a relatively large excitons binding energy (60meV) at room temperature which is attractive for optoelectronic applications. Likewise, cupric oxide (CuO), having a narrow band gap of 1.2 eV and a variety of chemo-physical properties that are attractive in many fields. Moreover, composite nanostructures of these two oxides (CuO/ZnO) may pave the way for various new applications. So in this thesis eight samples of CuO/ZnO junction were synthesized and exposed to temperatures 60, 70 80 90, 100, 110, 120 and 130. The electrical properties of Schottky diode junctions were analyzed by I–V measurements under the influence of direct solar radiation and, lag of radiation (darkness) which shows the semi–logarithmic I–V characteristic curve of the fabricated photodiodes. Also those samples ( CuO/d ZnO diodes) were exposed to temperatures 60, 70 80. 90, 100, 110, 120 and 130 to study the absorption, transmittance absorption coefficients and energy gap change with temperature it was found that the absorption coefficient increases while the energy gap decreases upon increasing temperature The morphology and particle sizes of the prepared samples were determined by SEM. The SEM images of ZnO+ CuO sample films were heated at (60, 70 80 90, 100, 110, 120 and 130 Co) temperatures are showed sphere-like ZnO+ CuO sample films uniform in both morphology and particle size, but have agglomeration to some extent. The average size was calculated to be (1.5 μm. 561 nm. 222 nm. 169 nm. 130 nm. 109 nm. 92 nm. 94.69 nm. respectively). Corresponding histograms, showing the particle size distribution, are also presented. The mean particle size which estimated from SEM is in close agreement with the average crystallite size as calculated from histograms line broadening. The microstructure and chemical composition of the film surface were analyzed using a scanning electron microscope (SEM, Tuscan Vega LMU). Their sizes are found to range from 109 to 124 nm.