Electrical characteristics of Au-PbPc-Au thin film sandwich devices on exposure to O2 and Cl2

The semiconducting characteristics of Au-PbPc-Au thin film sandwich devices were studied as a function of exposure to oxygen (in the form of air) and chlorine. Both O2 and Cl2 were found to generate acceptor levels within the PbPc bandgap. Both ohmic and space charge-limited conduction were observed. The experimental data were analysed within the framework of the model of Schmidlin and Roberts. Devices exposed to air for extended periods showed Schottky behaviour. The width of the Schottky barrier was estimated as60nm, the barrier height 15eV and the rectifying ratio at ±1 V was 200. The Schottky barrier disappeared after vacuum annealing at 423 K.