PEDOT:PSS Schottky contacts on annealed ZnO films

Polycrystalline ZnO and ITO films on SiO₂ substrates are prepared by radio frequency (RF) reactive magnetron sputtering. Schottky contacts are fabricated on ZnO films by spin coating with a high conducting polymer, poly(3, 4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) as the metal electrodes. The current-voltage measurements for samples on unannealed ZnO films exhibit rectifying behaviours with a barrier height of 0.72 eV (n=1.93). The current for the sample is improved by two orders of magnitude at 1 V after annealing ZnO film at 850 oC, whose barrier height is 0.75 eV with an ideality factor of 1.12. X-ray diffraction, atomic force microscopy and scanning electron microscopy are used to study the properties of the PEDOT:PSS/ZnO/ITO/SiO₂. The results are useful for applications such as metal-semiconductor field-effect transistors and UV photodetectors.