PEDOT-PSS Schottky Contacts On ZnO

ZnO is a direct wide bandgap compound semiconductor materials,at room temperature the band gap is about 3.37 eV, exciton binding energy is(60 meV). In recent years, ZnO nano-materials received extensive attention. It has potential applications in the UV emission and transparent conductive FET, also it can be used in photodetectors, electro-mechanical coupling sensors, and bio-mechanical transducer. Therefore, the preparation of high-quality ZnO Schottky contact structure is of great significance. In this paper, by using radio frequency magnetron sputtering method ITO films were prepared on SiO2 as conductive cathode,and then ZnO thin films,PEDOT-PSS thin films and Au films were respectively prepared by radio frequency reactive magnetron sputtering method,spin coating method and thermal evaporation method.At last Au/PEDOT-PSS/ZnO/ITO/SiO2 Schottky contacts were prepared.Divided into the following sections:(1) by radio frequency reactive magnetron sputtering ZnO thin films were prepared on glass and quartz substrates, By using X-ray diffraction(XRD), the structure of ZnO thin films with different oxygen partial pressure were analyzed. XRD results show that when the growth temperature of 200℃, growth atmosphere of Ar:O= 20:10 with the working pressure of 0.5Pa and the sputtering power of 95W, ZnO films have the smallest (002) diffraction Full-Width Half-Maximum and preffered (002) orientation.(2) The ZnO thin films were annealed at different temperature, Using X-ray diffraction (XRD) we analyzed the Influence of annealing to ZnO nano-structure. AFM and XRD results showed:after annealed at 850℃-nanostructured ZnO thin film's quality is better, ZnO thin films prepared by this way have good structural properties and high optical quality, which provides a feasible way for the further implementation of ZnO thin film devices.(3) By using spin coating method the PEDOT-PSS films were fabricated on glass substrates. A four-probe resistance measurement method was used to measure the resistivity of the film. The results show that:with the rotation speed increases, the thickness reduces, and film uniformity is better, film resistivity does not change significantly.(4) Schottky contacts were made by spin-coating PEDOT:PSS films on ZnO thin films. By theⅠ-Ⅴcurve testing the Influence of annealing to the Schottky contact characteristics were analysised. The results show:850℃oxygen atmosphere annealing makes the optical characteristics of the Schottky junction a significantly increase. The results show that with ZnO thin films annealed at 850℃oxygen atmosphere the Schottky junction's reverse saturation current decreases from 1-36×10-6 to 8.48 x 10-8, and the ideal factor n decreases from 1.93 to 1.16, and the barrier height increases from 0.72eV to 0.79eV.