ZINC-OXIDE THIN-FILMS PREPARED BY THE ELECTRON-CYCLOTRON-RESONANCE PLASMA SPUTTERING METHOD

Zinc oxide (ZnO) thin films have been prepared by a sputtering deposition utilizing electron-cyclotron-resonance (ECR) plasma. An X-ray diffraction analysis indicated that the ZnO films were highly c-axis oriented. The electrical resistivity of ZnO films is as high as 2.5 MΩcm. It is confirmed that the ZnO films exhibit strong piezoelectricity. For a film-thickness-to-wavelength ratio h/λ of about 0.16, the effective electromechanical coupling coefficient k2 for a surface acoustic wave was 0.7%, which is above 90% of the calculated value. The measured values of k2 are comparable to those of the films fabricated by other conventional sputtering methods. In addition, optical emission spectroscopy was carried out during the deposition. © 1990 The Japan Society of Applied Physics.