The influence of film crystallinity on the coupling efficiency of ZnO optical modulator waveguides

Abstract

The coupling efficiencies of sputtered, c-axis-orientated zinc oxide (ZnO) films in guided wave resonance optical modulators have been measured. The ZnO planar waveguide is sandwiched between two 3 nm thick chromium layers on top of a Si02p(100) substrate. This novel design facilitates application of a modulation voltage directly across the dielectric film in a prism coupler set-up and thus avoids voltage losses across the silicon dioxide (SO,) optical isolation layer.We present a comparison of four differently prepared ZnO waveguideslmodulators to investigate the influence of film crystallinity on the coupling efficiency and electro-optical parameters. The coupling efficiency of a ZnO waveguide is found to be dependent on both film thickness and average grain diameter measured in the plane of the film. A high efficiency (0.76) can be achieved for film thicknesses below 300 nm when the average grain diameter is 26 nm. This value is comparable to the maximum value of tvDicallv around 0.

Hydrothermal growth of ZnO nanostructures

“…ZnO is transparent to visible light and its conductivity can be increased through doping. ZnO nanostructures have a wide range of high technology applications like surface acoustic wave filters [1], photonic crystals [2], photodetectors [3], light emitting diodes [4], photodiodes [5], gas sensors [6], optical modulator waveguides [7], solar cells [8,9] and varistors [10]. ZnO is also receiving a lot of attention because of its antibacterial property and its bactericidal efficacy has been reported to increase as the particle size decreases [11].…”

Photoluminescence emission at aging in ambient air of ZnO:Ag nanocrystals obtained by ultrasonic spray pyrolysis

“…ZnO NCs are promising candidates for the different optoelectronic applications such as light emitting diodes [2][3][4][5][6][7]. The control of the ZnO defect structure in these nanostructures is a necessary step in order to improve the device quality.…”

Hydrothermally Synthesis Nanostructure ZnO Thin Film for Photocatalysis Application

“…Therefore, ZnO has been widely investigated for photo electrochemical water splitting in photoelectrolysis. Recently efficiency of ZnO in photoelectrochemical hydrogen production is still low as a result of its relatively not more light harvesting capability and quick recombination of photo-created carriers [10]. But the ZnO shows low efficiency because its thermodynamical unstable in electrolyte solution and photo degradation.…”