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 °C, 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.