We reported that zinc oxide (ZnO) films deposited by direct current (DC)-mode electrocyclotron resonance (ECR) and radio frequency (RF)-mode ECR sputtering systems had shown excellent piezoelectric properties and c-axis orientations. The RF-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 fundamental Rayleigh surface acoustic wave (SAW). In this paper, we investigate the properties of ZnO film deposited by an RF-magnetron-mode ECR sputtering system which has added magnets to the outside of a cylindrical zinc metal (Zn) target of the RF-mode ECR sputtering system. The 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 frequency than the previously reported ZnO film. This film exhibits most of the same effective electromechanical coupling factors (keff) as the theoretical keff values calculated by finite-element method (FEM) using the constants of ZnO single crystal (that is, 97 percent of theoretical value) and 0.6∼3.6 dB lower insertion loss in comparison with the films deposited by the DC-mode ECR and the RF-mode ECR. 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 property of a thin, 1.2-μm, epitaxial ZnO film, free exitons are observed for the first time.
|ジャーナル||Electronics and Communications in Japan, Part II: Electronics (English translation of Denshi Tsushin Gakkai Ronbunshi)|
|出版ステータス||Published - 1996 7|
ASJC Scopus subject areas
- コンピュータ ネットワークおよび通信