Emission and defects of nanostructures thin films of ZnO and ZnO-Cu obtained at low temperature

ABSTRACT

Thin films of ZnO and ZnO-Cu are reported with thicknesses between 220-630 nm approximately and well adhered on glass substrates. The synthesis was carried out by the sol gel process at room temperature and deposited using the spin coating technique. All ZnO and ZnO-Cu films obtained have luminescence in the range between 520 - 550 nm with intensities that are related to the number of layers deposited on the substrate. However, the incorporation of Copper intensifies the emission of photoluminescence in the visible range. The decrease in the UV emission of ZnO (380 nm) is attributed to the non-radiative recombination of the process caused by the Cu atoms. By XRD, it was found that the incorporation of Cu ions to the precursor solution did not significantly affect the crystalline structure of the films (wurtzite). The Raman spectroscopy analysis of the films reports the emission in the Bg and Bu' mode located at 327 and 466 cm^-1, which corresponds to CuO. The SAED rings of the HRTEM images of the ZnO-Cu films have CuO diffraction in the (020) plane and confirm the results shown in Raman spectroscopy. These materials, thus obtained, can have applications in the development of optical and energy devices for use in luminescent screens and contribute to the generation of innovation in materials using green technology.

Keywords
Luminescent screens; eco-friendly processes; ZnO:Cu nanoparticles by HRTEM