Microstructural investigation of ZnO films grown on (1 1 1) Si substrates by plasma-assisted molecular beam epitaxy

• Published in: Journal of crystal growth 2010-04, Vol.312 (9), p.1557-1562
• Main Authors: Mo Yang, Sang, Kyu Han, Seok, Wook Lee, Jae, Kim, Jung-Hyun, Goo Kim, Jae, Hong, Soon-Ku, Yong Lee, Jeong, Song, Jung-Hoon, Ig Hong, Sun, Sub Park, Jin, Yao, Takafumi
• Format: Article
• Language: English
• Subjects: A1. Characterization; A3. Molecular beam epitaxy; B1. Oxides; B1. Zinc compounds; B2. Semiconducting II–VI materials; Condensed matter: structure, mechanical and thermal properties; Cracks; Cross-disciplinary physics: materials science; rheology; Crystal structure; Electron diffraction and scattering; Epitaxy; Exact sciences and technology; Low-energy electron diffraction (leed) and reflection high-energy electron diffraction (rheed); Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Oxidation; Physics; Silicon substrates; Structure and morphology; thickness; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Thin film structure and morphology; Transmission electron microscopy; Zinc; Zinc oxide
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2010.01.048

Microstructural analyses of of ZnO films on (1 1 1) Si substrates grown by plasma-assited molecualr beam epitaxy were performed in this study. Zn pre-deposition and its subsequent oxidation, in which either oxygen gas or oxygen-plasma was used as the oxygen source, were employed before ZnO growth. Both reflection high energy electron diffraction and x-ray pole figure showed the single crystalline features in the ZnO films with both post-oxidation of deposited Zn. Detailed transmission electron microscopy (TEM), however, revealed a locally multi-crystalline feature with 30 degrees-rotated domians at the near-interface regions in the ZnO film with oxidation by oxygen gas. ZnO film with oxidation of pre-deposited Zn by oxygen-plasma was observed to be single crystalline through the whole thickness by TEM. We observed a new epitaxial relationship, (0 0 0 1)ZnO//(1 1 1)Si and [0 1 1¯ 0]ZnO//[1 1¯ 0]Si, with a crystallographic rotation of ZnO with respect to Si by 30 degrees, which is energitically more favorable because of a lower lattice misfit (2.2%). No cracks were observed from the ZnO film with a thickness of 1.5 μm, supporting the mechanical integrity of the film prepared in this study.