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 10(3) 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 x 10(14) cm Hz(1/2)/W at 370 nm. (C) 2008 American Institute of Physics.