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Interface Engineering in ZnO Epitaxy
Author(s) -
Hong S.K.,
Chen Y.,
Ko H.J.,
Yao T.
Publication year - 2002
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200201)229:2<803::aid-pssb803>3.0.co;2-r
Subject(s) - sapphire , epitaxy , materials science , molecular beam epitaxy , optoelectronics , electron diffraction , diffraction , layer (electronics) , crystallography , nanotechnology , chemistry , optics , laser , physics
We report interface engineering in ZnO epitaxy to grow high‐quality layers by plasma‐assisted molecular beam epitaxy. Through interface engineering, we have succeeded in two‐dimensional layer‐by‐layer growth of ZnO both on sapphire and GaN, and control of lattice polarity of ZnO films on a Ga‐polar GaN template. MgO buffer has been used to convert the growth mode from a three‐dimensional to a two‐dimensional mode in ZnO epitaxy on sapphire. O‐plasma pre‐exposure on Ga‐polar GaN templates has been employed to form a monoclinic Ga 2 O 3 interface layer at the ZnO/GaN heterointerface, while Zn pre‐exposure prevents oxidation of the GaN surface resulting in a ZnO/GaN heterointerface without an interface layer. The lattice polarity of ZnO films on Ga‐polar GaN templates with and without a Ga 2 O 3 interface layer with inversion symmetry have been revealed as Zn‐ and O‐polar, respectively, by coaxial impact collision ion scattering spectroscopy. Structural properties of ZnO films grown with MgO buffer on sapphire or with Zn pre‐exposure on GaN templates are better than those grown without MgO buffer or with an O‐plasma pre‐exposure, respectively. A buffer mechanism of MgO is discussed based on reflection high‐energy electron diffraction and high‐resolution X‐ray diffraction analyses, while the mechanism for controlling the polarity in ZnO epitaxy is discussed using an interface layer with inversion symmetry. It is suggested that the present method offers a general approach to control the crystal polarity.