As-grown CVD ZnO optical waveguides on sapphire

Optical-waveguide loss was measured in as-grown single-crystalline ZnO films which were chemical-vapor-deposited on intermediately sputter-deposited very thin ZnO films on sapphire substrates. The obtained minimum attenuations at 6328 Å are 18.3, 14.2, 10.7, 8.7, 4.7, 2.4, 1.5, and 0.7 dB/cm for the seventh, sixth, fifth, fourth, third, second, first, and zeroth TE modes, respectively, in a 2.57-μm-thick ZnO film. A strip waveguide was made of the CVD ZnO film selectively grown on an intermediately sputter-deposited ZnO pattern on sapphire.