| ZnO is a promisingâ…¡-â…¥compound semiconductor material with the properties of direct wide-band gap (3.37eV at 300K), has a large exciton binding energy at room temperature (60meV). ZnO is difficult to be oxidated at the atmosphere and it also has high heat and chemical stability. It has been extensively studied in recent years for various optoelectronic applications, such as, ultraviolet light-emitting diodes (LEDs) and laser diodes, thin film transistors, ultraviolet detectors, diluted magnetic semiconductors (DMS) and gas sensors, etc. There are many growth methods for ZnO films such as magnetron sputtering, chemical vapor deposition, sol-gel, spay pyrolysis, thermal oxidation and molecular beam epitaxy (MBE). Recently, some new growth methods such as pulsed laser deposition (PLD), metal organic chemical vapor deposition (MOCVD), atomic layer epitaxy and laser molecular beam epitxay have been widely used.The goals of this work are to synthesize the pure ZnO, ZnO:Mg and ZnO:Mg on glass substrates in the forms of thin films by using RF magnetron sputtering technique and to study the structural, stoichiometric, optical properties of these thin films for the potential applications in the new optoelectronic devices. The main contents include:(1) The structural and morphology of the samples are investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the stress in the ZnO thin films was analyzed. The results show that all the samples have a strong diffraction peak and high preferential orientation in the (0 0 2) crystallographic direction. For the ZnO:Cu films, with the increase of the Cu doped in ZnO, the XRD diffraction peak intensity increased and the peak width at half height (FWHM) became large. Meanwhile the crystallinity becomes worse and the grain becomes small. The ZnO:Cu films had the worst crystallinity and the grain size is smallest when the doping Cu 2at%. The crystallinity becomes better and the crystalline grain size becomes larger when Cu concentration increasing. But for the ZnO:Mg films, the peak width at half height (FWHM) becomes small with the increase of the Mg concentration. Meanwhile the crystallinity becomes better and the grain becomes large. When the doping Mg 16at%, the ZnO:Mg films has the best crystallinity and the grant size is largest. The crystallinty becomes worse and the crystalline grain size becomes small when Mg concentration increased.(2) Four peaks have been observed from the PL spectra of the ZnO:Mg films, 356nm (3.45eV, ultraviolet), 389nm (3.14 eV, ultraviolet), 444nm (2.78eV, blue) and 49088 nm (2.54eV, blue and green). Three peaks have been observed from the PL spectra of the ZnO:Cu films, 395nm (3.14eV, violet), 444nm (2.78eV, blue) and 488nm (2.54eV, blue). It is concluded that the violet peak may correspond to the exciton emission; the blue emission corresponds to the electron transition from the bottom of the conduction band to the acceptor level of zinc vacancy.(3) The the optical band gap test shows that the optical band gap Eg decreases within the increase of Cu doped in ZnO, the band gap decreases from 3.26eV to 2.99eV gradually. We also find that the transmission rate decreases rapidly when the Cu concentration increasing. Meanwhile the optical band gap E_g increases within the increasing of Mg doped in ZnO, the band gap increase from 3.26eV to 3.81eV gradually. So by controlling the concentration of Cu and Mg one can modulate the E_g. In the visible region, the average transmittance of the ZnO:Mg films excees 92%, respectively. This is because the band gap of ZnO is higher than the energy of the visible region. So the light absorption is mainly free carrier absorption in the visible region. However, the ZnO films'mobility rate of free carrier is so high that the absorption coefficient of free carrier is very small.
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