Zinc oxide films were grown on sapphire substrates by direct current magnetron sputtering and irradiated by electrons with energy 10 MeV and fluences 10^{16} and 2 × 10^{16} cm^{-2}. As-grown and irradiated samples were investigated by X-ray diffraction and photoluminescence spectroscopy. It was found that radiation causes the appearance of complex defects, reducing the size of coherent scattering regions and the increase of the defect PL band.
ZnO films doped with the cadmium (0.4-0.6%) were grown on crystalline sapphire c-Al_2O_3 substrates applying radiofrequency magnetron sputtering at the temperature of 400°C in Ar-O_2 atmosphere. The as-grown films were investigated in detail using X-ray diffraction, X-ray photoelectron spectroscopy, and cathodoluminescence spectra. The X-ray diffraction analysis revealed that the films possess a hexagonal wurtzite-type structure with the dominant crystallite orientation along the c axis. It was found that the small concentration of the cadmium significantly enhances the ultraviolet emission associated with excitonic transitions. We suggest that this enhancement effect mainly results from appearance of the cadmium isoelectronic traps, which may bind an exciton, thereby increasing the probability of radiation recombination. The effect of Cd isoelectronic impurity on structural and luminescent properties of ZnO films is discussed.
Zn_{0.9}Cd_{0.1}O ternary alloys have been grown on the sapphire substrates by using the direct current (dc) magnetron sputtering. X-ray diffraction measurements showed that all samples were highly oriented films along the c-axis perpendicular to the substrate surface. X-ray diffraction confirmed that the crystal quality of Zn_{0.9}Cd_{0.1}O films can be controlled by changing the gas ratio of Ar/O_2. The optical properties of these films have been investigated by means of the optical transmittance and the low-temperature photoluminescence spectra. It was found that the optical band gap of the deposited films can be tuned by growth parameters. The luminescence processes are considered in the terms of alloy fluctuation.
Optical properties of ZnO films doped by Al in the range 0.5 to 7 at.% and deposited by atomic layer deposition were studied in visible and infrared spectral range. Spectral dependences of film optical permittivity were modeled with the Lorentz-Drude approximation resulting in ZnO:Al plasma frequency and plasma damping parameters. We observed changing electron effective mass from 0.29m₀ to 0.5m₀ with increasing electron concentration in the range (0.9-4) × 10²⁰ due to the phenomenon of conduction band non-parabolicity. Comparing the results of optical and electrical investigations we can see that the main scattering mechanism is the scattering on grain boundaries (its contribution is about 60%).
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.