Obtaining of cds/cuo heterojunction structure and investigation of physical properties

CdS and CuO films have been grown onto microscope and fluorine doped tin oxide coated glass substrates using the chemical bath deposition method. Crystal structures of the CdS and CuO have been determined face-centered cubic and simple base-centered monoclinic structure respectively, and lattice constants, crystallite sizes, strains and dislocation densities calculated by xrd diffraction patterns. The forbidden energy gaps of films have been estimated. The films have exhibited direct band transition and the optical band gap values of the CdS are calculated 2.39 and 2.35eV for glass and FTO, respectively. Also, the band gap values of the CuO films are 1.61 and 1.26eV for glass and FTO, respectively. Traps are defined from the photoluminescence measurements of the films. The surface morphology analyses of the films have been investigated by atomic force microscopy and field emission scanning electron microscopy. The p-CuO/n-CdS stucture has been obtained on the FTO by CBD method and the gold contacts were evaporated as top electrode on the n-CdS. Trap density of CdS and CuO have been found to be 1.04×1021 and 3.18×1025 m-3 respectively, trap energy levels is 0.61eV below conduction band for CdS and 0.31eV above valance band for CuO. From the C-V measurements, the Vbi value was calculated to be 0.43V for CdS and 0.68V for CuO. It has been determined that the traps in the CdS from the G-f measurements show an non-uniformly distribution inside the forbidden energy gap. The diode ideality factor of the FTO/p-CuO/n-CdS/Au structure has been estimated 3.53 from the I-V measurements.