Design and Fabrication of Edge Coupling ZnO Traveling Wave Photodetectors

In this paper, we reported on the design and fabrication of the edge coupling traveling wave ZnO photodetectors(TWPD). In this device structure, the incident light propagates and gets absorbed along the longitudinal direction of a ZnOlayer. Unlike the conventional photodetectors (i.e., vertical illumination onto detector surface), light absorption is not limitedby the film thickness or by the blocking of the incident light through the metal electrodes, but can reach near 100 %. Anotheradvantage of this structure is that it can be easily integrated with other waveguide structures for optical inputs and/orelectrical outputs. The key parameters for designing the edge coupling ZnO TWPD were characterized. These requirementsare good ohmic contacts, low dark current and high photoresponse.