In this study, epitaxial ZnO films were grown by chemical vapor deposition (CVD) on LSAT(100) substrate. A high-quality [100] (La0.3,Sr0.7)(Al0.65,Ta0.35)O3 (LSAT) single crystal with the diameter of 60mm was grown by Czochralski pulling technique in our lab. Epi-ready LSAT substrates with rms roughness of 0.30nm ~ 0.35nm were used for all of the experiments. Nonpolar ZnO with [11-20] orientation (a-plane) was directly grown on a (100) LSAT substrate without any buffer layer by chemical vapor deposition (CVD) method. (100) LSAT single crystal substrate is loaded in a 2¡¨ quartz tube inserted to a two-temperature zone furnace. Zinc acetylacetonate hydrate (Zn(C5H7O2)2¡DxH2O, Lancaster) source was vaporized at the lower temperature of 130~140oC. The vapor was carried by a mixture of N2/O2 gas flow into the high temperature zone where the (100) LSAT substrate was located. At first, the pressure of the quartz chamber was pumped to 8¡Ñ10-3 Torr, and then kept at 150 ~ 250 Torr. The flows rates of both O2 and N2 are 500sccm. During the growth, the temperature was varied from 700 to 780oC. The growth conditions were controlled by adjusting the growth temperatures and chamber¡¦s pressures. The overall reaction was:
Zn(C5H7O2)2 +12O2¡÷ZnO+ 10CO2 +7H2O
Scanning electron microscope [(SEM), JEOL JSM-6330TF)] is used to examine the different surface morphologies of ZnO epitaxial film. The orientation and structure were investigated by X-ray diffraction pattern (XRD) using a Siemens D5000 X-ray diffractometer with a Cu anode at 40 kV and 30 mA. The wavelength of X-ray radiated from the Cu K£\1 is 0.1540 nm. The X-ray scan step is 0.01¢X. A JEOL 3010 scanning transmission electron microscope (STEM) operated at 200kV was employed to characterize the microstructures and orientation of the nonpolar ZnO film. Cross-sectioned TEM samples were prepared using the focus ion beam lift-out method. A Pt layer of about 8nm in thickness was pre-deposited on the sample to prevent charging. Room temperature photoluminescence (RT-PL) measurements were performed using a 325nm He-Cd laser. The emitted light was detected by a Jobin-Yvon TRIAX 550 monochromator with 0.025nm resolution.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0809110-170121 |
| Date | 09 August 2010 |
| Creators | Wang, Shih-chuan |
| Contributors | Pou-Yan Shen, Jih-Jen Wu, Der-Shin Gan, Ming-Chi Chou, Liu-Wen Chang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0809110-170121 |
| Rights | not_available, Copyright information available at source archive |
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