TY - JOUR
T1 - In-plane and polar orientations of ZnO thin films grown on atomically flat sapphire
AU - Ohkubo, I.
AU - Ohtomo, A.
AU - Ohnishi, T.
AU - Mastumoto, Y.
AU - Koinuma, H.
AU - Kawasaki, M.
N1 - Funding Information:
This work was partly supported by JSPS Research for the Future Program in the Area of Atomic-scale Surface and Interface Dynamics (RTFT96P00205). A.O. and T.O. are supported by JSPS Research Fellowships for Young Scientists. We thank M. Yoshimoto for providing us access to the CAICISS equipment.
PY - 1999/12/10
Y1 - 1999/12/10
N2 - Epitaxial ZnO thin films were prepared on atomically flat sapphire (0001) substrates at various temperatures by laser molecular beam epitaxy. On the as-polished substrates, the in-plane orientation of ZnO thin films was found to be ZnO [1010]∥sapphire [1120] regardless of the deposition conditions. However, films on atomically flat substrates showed two in-plane orientations, ZnO [1010]∥sapphire [1010] and ZnO [1010]∥sapphire [1120], rotated by 30° for films grown at low (400-450° C) and high (800-835° C) temperatures respectively. Ion scattering spectroscopy revealed that the former films were (0001) oriented with the Zn-face forming the topmost surface, whereas the latter films had the (0001) orientation with the O-face at the film surface. This orientation change is discussed by taking thermodynamic stability and growth kinetics into account. The films grown at very high temperature (835°C) showed superior crystallinity even in comparison with bulk single crystals.
AB - Epitaxial ZnO thin films were prepared on atomically flat sapphire (0001) substrates at various temperatures by laser molecular beam epitaxy. On the as-polished substrates, the in-plane orientation of ZnO thin films was found to be ZnO [1010]∥sapphire [1120] regardless of the deposition conditions. However, films on atomically flat substrates showed two in-plane orientations, ZnO [1010]∥sapphire [1010] and ZnO [1010]∥sapphire [1120], rotated by 30° for films grown at low (400-450° C) and high (800-835° C) temperatures respectively. Ion scattering spectroscopy revealed that the former films were (0001) oriented with the Zn-face forming the topmost surface, whereas the latter films had the (0001) orientation with the O-face at the film surface. This orientation change is discussed by taking thermodynamic stability and growth kinetics into account. The films grown at very high temperature (835°C) showed superior crystallinity even in comparison with bulk single crystals.
KW - Diffraction and reflection
KW - Ion scattering spectroscopy
KW - Single crystal epitaxy
KW - X-ray scattering
KW - Zinc oxide
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U2 - 10.1016/S0039-6028(99)01024-9
DO - 10.1016/S0039-6028(99)01024-9
M3 - Article
AN - SCOPUS:0001183311
SN - 0039-6028
VL - 443
SP - L1043-L1048
JO - Surface Science
JF - Surface Science
IS - 1-2
ER -