Abstract
Zn (1−x)CdxO solid solutions have been grown by us on Zn- and O-polar surfaces of ZnO substrate by metal organic chemical vapor deposition (MOCVD), with the same cadmium flow. We carried out photoluminescence spectroscopy (PL) and optical transmission measurements to investigate the incorporation of cadmium in the layers, as well as its influence on the optical properties. The lattice parameters and the morphology of these films were examined using high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). In our case, the Cd incorporation is obtained at 2.5% for Zn(1−x)CdxO grown on the Zn-polar surface of ZnO substrate, which is confirmed by the greatest energy shift (237meV) toward lower energies of the PL emission, and by the appearance of a new peak located at 270cm−1 in the Raman spectra. HRXRD studies show that all layers exhibit a wurtzite phase with c-axis orientation. In particular, regarding the Zn0.975Cd0.025O layer grown on Zn-face, the in-plane lattice parameter remains unchanged while the c-axis parameter is elongated to 5.399Å.
•Zn(1−x)CdxO films have been grown on Zn- and O-polar surfaces of ZnO substrates.•Higher Cd incorporation (2.5%) is obtained for ZnCdO grown on Zn-polar surface.•Cd incorporation is confirmed by the PL emission and by the Raman spectra.•X-ray diffraction study reveals that the film exhibits a wurtzite phase.•The lattice parameter c-axis is elongated to 5.399˚ for ZnCdO grown on Zn-polar surface.