Structural anisotropy in a -Mg x Zn 1 − x O ( 0 ≤ x ≤ 0.33 ) films on r -sapphire

• Published in: Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena Microelectronics and nanometer structures processing, measurement and phenomena, 2009-05, Vol.27 (3), p.1620-1624
• Main Authors: Saraf, Gaurav, Siegrist, Theo, Lu, Yicheng
• Format: Article
• Language: English
• ISSN: 1071-1023; 1520-8567
• DOI: 10.1116/1.3137013

The a -plane Mg x Zn 1 − x O ( 0 ≤ x ≤ 0.25 ) films were grown on r -plane ( 01 1 ¯ 2 ) sapphire substrates using metal-organic chemical vapor deposition. Growth was done at temperatures from 520   ° C , with a typical growth rate of ∼ 500   nm / h . Film thickness was varied by changes in deposition time, while Mg/Zn metal-organic flow was varied for changes in Mg composition. The a -plane films are dense and uniform. Strain anisotropy in the films was characterized by synchrotron x-ray diffraction. In-plane strain anisotropy increases with an increase in ZnO film thickness and reduces with an increase in Mg composition of Mg x Zn 1 − x O . The surface of the films characterized by atomic force microscopy showed rippled morphology with needles running along the surface. The morphology anisotropy in the films increases with an increase in ZnO film thickness and reduces with Mg composition of Mg x Zn 1 − x O films. The morphology anisotropy with ZnO film thickness and Mg composition of Mg x Zn 1 − x O is correlated with respective strain anisotropy variation.