Growth of epitaxial ZnO films on Si (111) substrates with Cr compound buffer layer by plasma-assisted molecular beam epitaxy

Abstract

Single crystalline ZnO film was grown on (1 1 1) Si substrate through employing an oxidized CrN buffer layer by plasma-assisted molecular beam epitaxy. Single crystalline characteristics were confirmed from in-situ reflection high energy electron diffraction, X-ray pole figure measurement, and transmission electron diffraction pattern, consistently. Epitaxial relationship between ZnO film and Si substrate is determined to be (0 0 0 1)(ZnO)||(1 1 1)(Si) and [1 1 (2) over bar 0](ZnO)|| [0 1 1](Si). Full-width at half-maximums (FWHMs) of (0 0 0 2) and (1 0 (1) over bar 1) X-ray rocking curves (XRCs) were 1.379 degrees and 3.634 degrees, respectively, which were significantly smaller than the FWHMs (4.532 degrees and 32.8 degrees, respectively) of the ZnO film grown directly on Si (1 1 1) substrate without any buffer. Total dislocation density in the top region of film was estimated to be similar to 5 x 10(9) cm(-2). Most of dislocations have a screw type component, which is different from the general cases of ZnO films with the major threading dislocations with an edge component. (C) 2010 Elsevier B.V. All rights reserved.