Transparent polymer Schottky contact for a high performance visible-blind ultraviolet photodiode based on ZnO

We report on a high performance visible-blind Schottky ultraviolet photodiode composed of a ZnO (0001) bulk single crystal and a transparent conducting polymer, poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), fabricated with a simple spin-coating process at room temperature in air. The quantum efficiency as high as unity in ultraviolet region and a visible rejection ratio of about 103 were achieved in the spectral response of the photodiode under zero-bias condition. The normalized detectivity of the photodiode was evaluated to be 3.6×1014 cm Hz1/2/W at 370 nm.