The effect of surface morphology in copper oxide nanostructure to photo detector characteristics

We study the effect of structural properties of copper oxide nanostructure and its sensitivity for photo detector application. Copper oxide (CuO) nanostructures were prepared by combining the thermal evaporation with dry oxidation. We select CuO system at different thickness (around 90, 170, and 270 nm) and X-ray diffraction spectra confirms their polycrystalline structure. Scanning electron microscope images show the distinct CuO morphology surface for each sample on which the grain shape is changed and the size is grown with the increasing of the CuO thickness. Fourier-transform infra-red spectra reveals the high penetration depth of oxygen at ~90 nm thick sample indicated by large Si-O-Si bond intensity. Photo current characterization for each sample is carried out to compare its light sensing properties. We found that the thickness of CuO nanostructure system is related to the sensitivity of device during the light exposure in which thinner samples have better performance. Furthermore different band gap for each CuO sample is predicted from its sensitivity at continuous light exposure. We suggest that the grain boundary and the distinct morphology might promote a unique confined nanostructure effect, resulting in band gap widening. These studies demonstrate a new approach for tunable photonic device efficiency that could be beneficial in reducing energy loss during energy conversion.