Properties of high quality ZnO films deposited by an RF magnetron mode electron cyclotron resonance (ECR) sputtering system

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 reported previously, are investigated. The ZnO film on the glass substrate deposited by this system was capable of driving a 1.3 GHz fundamental Rayleigh SAW for the first time. These films exhibit almost 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 and lower insertion loss in comparison with the films deposited by the DC-mode ECR and the RF-mode ECR. The ZnO film on R-plane sapphire deposited by this system shows a (112¯0) plane epitaxial ZnO film, which is capable of driving a 2.54 GHz Sezawa wave. By measuring a photoluminescence of a thin epitaxial ZnO film with thickness of 1.2 μm, free excitons are observed for the first time