Morphology and Luminescence of ZnO Films Grown on a Au(111) Support

Using scanning tunneling microscopy and spectroscopy, we have analyzed the growth of ZnO thin films on a Au(111) support. Because of the 12% lattice mismatch with the metal beneath, ZnO develops a (0001)-oriented coincidence lattice that gives rise to a well-ordered hexagonal Moiré pattern with 2.2...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2013-05, Vol.117 (20), p.10552-10557
Main Authors: Stavale, Fernando, Pascua, Leandro, Nilius, Niklas, Freund, Hans-Joachim
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Exact sciences and technology
Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties
Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of bulk materials and thin films
Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
Physics
Structure of solids and liquids
crystallography
Surfaces and interfaces
thin films and whiskers (structure and nonelectronic properties)
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Summary:Using scanning tunneling microscopy and spectroscopy, we have analyzed the growth of ZnO thin films on a Au(111) support. Because of the 12% lattice mismatch with the metal beneath, ZnO develops a (0001)-oriented coincidence lattice that gives rise to a well-ordered hexagonal Moiré pattern with 2.2 nm periodicity. This superstructure disappears at 4 ML film thickness, when wide, atomically flat terraces delimited by straight monatomic steps become detectable in the STM. The long-range order of the films is deduced from sharp hexagonal spot patterns in low-energy electron diffraction. STM-based luminescence and conductance spectroscopy reveals that the ZnO band gap approaches the bulk value in films thicker than 10 ML. Additional photon peaks with sub-band-gap energies indicate the presence of defects in the wurzite lattice. The intrinsic polarity of the ZnO(0001) surface is accounted for by a reduced Zn–O interlayer distance and an adsorption-mediated compensation scheme in thin and thick films, respectively.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp401939x