Luminescent Characteristics of Pulsed Laser Deposited Epitaxial Eu-Doped Y 2 O 3 Films
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11 Mat. Res. Soc. Symp. Proc. Vol. 574 ©1999 Materials Research Society
mTorr was maintained in the growth-chamber during deposition experiments. Assuming a timedependent linear film-growth, the growth-rate of the film deposited was estimated by dividing the total thickness of the film by the deposition time. The thicknesses of Eu:Y 2 0 3 films were measured using an ECI 10 multiwavelength ellipsometer. To check the reproducibility of the results, three samples prepared under identical deposition conditions were used for each measurement. The cathodoluminescence (CL) brightness of Eu: Y20 3 films was measured using an Oriel Multispec with a CCD detector. The CL was excited by primary electron beam with different energies (1-5 keV) and current density of 3.2 AiA/cm 2 . RESULTS AND DISCUSSION Shown in Fig. Ia is the (0-20) x-ray diffraction (XRD) scan of a 1.2 gm thick Eu:Y 2 0 3 film grown on (100) LaAIO 3 substrate at 750 0C. For comparison, we have also shown in this figure a standard XRD pattern of polycrystalline Y 2 0 3 powder (Fig. Ib). The (hO0) lines with h = 4, 6, and 8 are thickened to indicate that only these peaks appear in the XRD pattern of the Eu: Y 20 3 film besides the substrate peaks. This suggests a textured growth of Eu:Y 20 3 film on LaAIO 3 substrates. The films grown at lower temperatures (< 700 °C) were polycrystalline with wider full width at the half maximum (frhm) of each peak. Due limitation of our heater's capability to obtain higher temperature, we could not perform depositions at temperatures higher than 750 °C. The inset in Fig. I shows the rocking curve (co-scan) of the (400) peak of this film whosefwhm is only 0.20 confirming that Eu:Y 20 3 films are highly textured. (a)'
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Fig. I. X-ray diffraction patterns of (a) a 3.2 gim thick Eu: Y20 3 film grown on (100) LaAIO 3 substrate at 750 °C and (b) Y20 3 powder. The inset in Fig. 1(a) is the rocking curve of the (400) peak of the same film.
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The degree of in-plane alignment was determined using 0-scan of {222} peaks with 0 rotation axis parallel to the film thickness. The 0-scan result obtained from the same film, whose . XRD pattern is shown in Fig. la, is •. displayed in Fig. 2. Although the fwhm " values of the peaks in the 0-scan are >1 wider than those normally reported for " 0o_ o 900 > epitaxial oxide films' 2, the appearance of E only four peaks suggests that Eu:Y 20 3 • films grow epitaxial on LaA103 substrates if an optimized set of 6........"66'' "16 2 , Phi (degree) parameters during the deposition is used. from peak Further, the separation of each one another by 900 suggests a cube-on- Fig. 2. 0-scan of a 3.2 lgim thick Eu:Y 20 3 (222) family cube epitaxial relationship between the reflections of the film grown at 750 °C on (100) LaAIO 3 film and the substrate. The widerfivhm substrates. values of peaks in 0-scan may be due to
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