Growth of c-axis orientation ZnO films on polymer substrates by radio-frequency magnetron sputtering

ZnO films with c-axis orientation were deposited successfully on benzocyclobutene (BCB) and highly fluorinated polyether (HFP) substrates by radio-frequency magnetron sputtering. The effects of the sputtering parameters (argon−oxygen gas flow ratio, sputtering power, and sputtering pressure) on the crystalline quality of the ZnO films were investigated by X-ray diffractometry, atomic force microscopy, and scanning electron microscopy. By using optimized sputtering conditions, uniform ZnO films with good c-axis orientation were formed on hard BCB substrates to a thickness as large as 3.0 μm. The ZnO films formed on soft HFP substrates, however, were always thinner than 1 μm. In addition, a ZnO/BCB channel optical waveguide was fabricated, which had a propagation loss of 7.3 dB/cm at the wavelength 1550 nm.