Synthese und Charakterisierung nanokristalliner transparenter Halbleiteloxide (English shop)

Preview

Table of Contents, Datei (7.9 KB)
Extract, Datei (89 KB)

In this work, the transparent semiconducting oxides ITO and doped ZnO were successfully produced as nanoscale powders by pyrolysis of organometallic precursors. ITO was prepared as extremely small particles with a narrow size distribution by means of a plasma-assisted variant of the CVS process, used here for the first time to produce oxide materials. In the search for cost-effective alternatives to ITO, doped ZnO powders were produced by a CVS process operating at atmospheric pressure. Process operation at atmospheric pressure was carried out for the first time in the Thin Films department. In addition, the option of dispersing the particles directly during synthesis, which is of interest for applications, could be realised. For ZnO powders as well, narrow grain size distributions with mean values of 10–30 nm were achieved. The size, the width of the distribution and the decomposition of undoped nanocrystalline ZnO samples were investigated and characterised as a function of the synthesis temperature. Temperatures of 1300 °C and above had increasingly negative effects on the width of the distribution and on the yield. These results represent new findings with respect to the decomposition temperature of 1800 °C for ZnO known from the literature. In general, the grain size shows a slight decrease with decreasing synthesis temperature. The influences of the doping elements Al, Ga and In on the properties of ZnO samples were investigated. A decrease in grain size with increasing doping level and with increasing deviation of the ionic radii of the doping elements was observed. Furthermore, a slight increase in the width of the grain size distribution with increasing dopant concentration was observed.