Magnetic, structural and optical behavior of cupric oxide layers for solar cells

Abstract

Room temperature ferromagnetic hysteresis is observed in CuO nano films synthesized through chemical strategy. The room temperature ferromagnetic behavior in CuO is quite a new observation without any doping, annealing or any other post preparation treatments. The observed magnetization value is 0.24 T which is obviously depicted that the nano-scale magnetic properties dependent on the shape and size of nano films. The morphological observations is depicted that the uneven ellipsoidal grains transformed to nano-sheet shaped grains. Atomic force microscopy (AFM) images are also strengthening the observation of shape variations due to bath temperature variation. The surface profile and grain contour images are verified the size and shape variations. Structural variations are precisely predicted by X-ray diffraction patterns and crystallinity of the films is discussed. The growth mechanism of nano sheet formation and physical phenomena are discussed. The luminescence properties variations are observed by photoluminescence (PL) spectroscopy and it has exposed that the bath temperature effects on the CuO films. X-ray photoelectron spectroscopy (XPS) spectra is depicted that Cu 2p3/2, Cu 2p1/2 and O1s related peaks at 929.50, 952.80 and 529.38 eV binding energy, respectively. In addition, the optical dielectric dispersion parameters such as effective mass (me), optical susceptibility (χe), carrier concentration (N), plasma frequency (ωp), relaxation time (τ) and frequency (f) are also evaluated. Raman scattering spectra revealed the Ag and Bg modes shift at 296 and 628 cm−1.