Chemical vapor deposition of ZnO epitaxial films on sapphire

摘要

A chemical vapor deposition system for the growth of epitaxial (112macr;0) ZnO films on (011macr;2) sapphire, employing the reaction of zinc vapor and carbon dioxide, was investigated. Growth rates as high as 30 mgr;m/h at a substrate temperature of 700hyphen;750thinsp;deg;C were achieved. Films grown on substrates with thin presputtered layers exhibited smooth surfaces and improved crystal perfection as determined by SEM, reflection electron diffraction, and acoustic evaluation. Films had high resistivity which eventually degraded on exposure to atmosphere. Surface acoustic wave interdigital transducers were fabricated on lithiumhyphen;diffused films, and the electromechanical coupling coefficient of 1.39percnt; was measured for a film thickness to wavelength ratio of 0.13.