Morphology transformation of Cu2O thin film: different environmental temperatures employing chemical method

Hydrothermal was used to synthesize cuprous oxide (Cu2O) by using copper powder (30 nm) and deionized water on at different temperatures (50 degrees C, 100 degrees C, 150 degrees C, and 175 degrees C) for 48 h. X-Ray diffraction revealed the formation of different Cu2O phases with strong diffraction peak at the (111) diffraction plane. Particle size increased from 17.4 nm to 43.6 nm with increasing temperatures. Raman spectra presented a unique chemical fingerprint and high-intensity peak appeared at 220 cm(-1), which attributed to Cu2O, this peak decreased and disappeared as the temperature increased above 100 degrees C. Different chemical bonds in Fourier Transform Infrared Spectroscopy measurement indicated the formation of Cu2O, with peaks at 630 and 1016 cm(-1). These peaks disappeared as the temperature increased. Energy bandgap estimated from the absorption spectra revealed a red shift, and bandgap values decreased from 2.6 to 2.2 eV with increase temperature, consistent with bandgap determined using photoluminescence method. The morphology was observed using scanning electron microscope. Different shapes, such as truncated octahedron, semispherical, and micro flowers, were formed. Atomic force microscopy showed that surface roughness increased from 5.1 to 90 nm as the reaction temperature increased. Electrical measurement showed increments in conductivity as the resistivity decreased and the reaction temperature increased. Activation energy levels determined based on DC measurement were 0.017, 0.06, 0.09, and 0.04 eV.