| Summary: | 碩士 === 國立臺灣師範大學 === 物理學系 === 105 === Pulsed-laser deposition (PLD) was applied to grow 100 nm thick Europium (Eu)-
doped ZnO (Eu:ZnO) thin films on c-sapphire substrate under 3×10-1 mbar of Oxygan. The Eu concentration ranges from 0 to 15 at.%, temperature of substrate is 750°C, and laser fluence is 1.6 J/cm2. The deposition rate, structural properties, optical properties and magnetic properties of Eu:ZnO thin films were investigated in this study.
Eu concentrations determined by the X-ray photoelectron spectroscopy (XPS) were slightly smaller than the nominal concentration. X-ray diffraction (XRD) and Raman-scattering spectra revealed Eu incorporation into ZnO without secondary phase. As Eu density increased, the grain size of Eu:ZnO thin films decreased. Photoluminescence (PL) spectroscopy showed that all the thin films had oxygen interstitials , zinc vacancies and oxygen vacancies. In addition, high Eu concentration thin films (8%,10%,15%) had zinc interstitials. By both spectroscopic ellipsometry and optical transmission spectroscopy, the direct band gap of Eu-doped ZnO thin films was found to increase with increasing Eu concentration. At T = 5 K and 300 K ,magnetic investigations with a superconducting quantum interference device(SQUID) magnetometer showed paramagnetism for all Eu-doped ZnO thin films.
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