Low-loss epitaxial ZnO optical waveguides on sapphire by rf magnetron sputtering

Abstract

Optical waveguide loss of about 0.55 dB cm−1 has been measured on epitaxial ZnO films on sapphire by magnetron sputtering. Measurements were also made of the refractive index of those films. The experimental results are compared with theory when TE and TM guided waves propagate in the plane at an arbitrary angle with respect to the c axis where the c axis is lying in the plane of the film. Surface acoustic wave (SAW) properties were also measured for SAW propagating along the c axis of ZnO film on the (011̄2)-oriented Al2O3 substrate.

Ultraviolet detectors based on epitaxial ZnO films grown by MOCVD

“…[1][2][3][4][5][6][7][8][9][10] Recently, there has been an increased interest in high quality ZnO films in order to utilize their optical properties resulting from ZnOs direct-and wideenergy bandgap. Because of its electrical, optical, and piezoelectric properties, ZnO has been used in a wide range of applications.…”

Surface and Interface Properties of Metal-Organic Chemical Vapor Deposition Grown a-Plane Mg x Zn1–x O (0 ≤ x ≤ 0.3) Films

“…Our results agree with the reported work, which indicates that ZnO films with thicknesses lower than 800 nm are under tensile strain along the in-plane m-axis and compressive strain along the c-axis. 9 The SAED patterns show sharp diffraction spots from the ZnO and Mg 0.30 Zn 0.70 O films as well as the r-sapphire substrate, indicating good overall crystallinity of the films. It can be observed that the diffraction spots of the films do not overlap with the diffraction spots of the r-sapphire substrate, indicating partial relaxation in the films, as observed in HRTEM images.…”

“…8 In addition to these advantages, the a-plane Mg x Zn 1)x O films possess in-plane anisotropic properties along the caxis and perpendicular to the c-axis, which can be used for novel optical, acoustic, and electrical devices. 9,10 The use of r-sapphire as a substrate for growth on nonpolar a-plane ZnO films is advantageous due to a lower overall lattice mismatch with ZnO as compared to commonly used c-sapphire substrate. The lattice mismatch between the r-sapphire and a-plane ZnO along the c-axis is~1.53%, while along the in-plane m-axis, it is~18.3%.…”

Characterization of ZnO films of surface acoustic-wave oscillators for ultraviolet sensing applications

“…1 ZnO thin films with a c-axis orientation have been used for acoustic wave applications such as surface acoustic wave ͑SAW͒ devices and thin film bulk acoustic wave resonators ͑FBARs͒. [2][3][4] Furthermore, the absorption wavelength of ZnO is approximately 385 nm, so it can be used for UV detection. ZnObased UV sensors that use photoconducting layers, a metalsemiconductor-metal phototransistor, and a Schottky barrier have been widely reported.…”