Optical properties of single-crystalline ZnO film smoothly chemical-vapor deposited on intermediately sputtered thin ZnO film on sapphire

Abstract

ZnO-Br2-O2, ZnCl2-O2, and ZnO-H2-H2O-O2 chemical-vapor-deposition (CVD) systems are studied to obtain as-grown optical waveguides of single-crystalline ZnO on sapphire. The waveguide is made on a very thin sputter-deposited epitaxial layer of ZnO on sapphire by using the ZnO-H2-H2O-O2 isothermal CVD system. The minimum loss obtained for the TE0 mode propagating perpendicular to the c axis in a (112̄0) ZnO film is 0.7 dB/cm. This chemical-vapor deposition of ZnO on a thin-sputtered ZnO film gives a method for the fabrication of strip waveguides on sapphire due to the selective growth of the ZnO films on sputter-deposited ZnO strips.