PROPERTIES OF ZINC-OXIDE FILMS DEPOSITED BY A RADIOFREQUENCY MAGNETRON MODE ELECTRON-CYCLOTRON-RESONANCE SPUTTERING SYSTEM

We reported that zinc oxide (ZnO) films deposited by direct current (D C)-mode electrocyclotron resonance (ECR) and radio frequency (RF)-mode ECR sputtering systems had shown excellent piezoelectric properties a nd c-axis orientations. The RE-mode ECR sputtering system was capable of depositing ZnO films on glass substrates without evidence of column and fiber grains in cross-section analysis while driving a 1.1-GHz fu ndamental Rayleigh surface acoustic wave (SAW). In this paper, we inve stigate the properties of ZnO film deposited by an RE-magnetron-mode E CR sputtering system which has added magnets to the outside of a cylin drical zinc metal (Zn) target of the RE-mode ECR sputtering system. Th e ZnO film on the glass substrate deposited by this system was capable of driving a 1.3-GHz fundamental Rayleigh SAW. This shows a higher fr equency than the previously reported ZnO film. This film exhibits most of the same effective electromechanical coupling factors (k(eff)) as the theoretical k(eff) values calculated by finite-element method (FEM ) using the constants of ZnO single crystal (that is, 97 percent of th eoretical value) and 0.6 similar to 3.6 db lower insertion loss in com parison with the films deposited by the DC-mode ECR and the RE-mode EC R. A (1120) plane epitaxial ZnO film was deposited at low temperatures on an R-plane sapphire substrate using this system and was capable of driving a 2.54-GHz Sezawa wave. By measuring the photoluminescence pr operty of a thin, 1.2-mu m, epitaxial ZnO film, free exitons are obser ved for the first time.