Fabrication of a heterostructure device with Au/PPani-TiO_2/ITO configuration and study of device parameters including current conduction mechanism

摘要

Polyaniline based composites incorporating titanium dioxide have been synthesized by an alternative pathway using reactive magnetron sputtering of titanium and plasma polymerization of aniline monomer. Structural, optical and morphological characterizations of plasma polymerized aniline (PPani) and titanium dioxide (TiO_2) composites (PPani-TiO_2) reveal the evidence for the incorporation of TiO_2 in the PPani matrix. A hybrid heterostructure device having PPani-TiO_2 composite with a top gold (Au) layer and bottom indium-tin oxide (ITO) layer is fabricated. The developed heterostructure device exhibits rectifying behaviour indicating the formation of a Schottky contact between Au and PPani-TiO_2. The detailed electrical measurement of the device is performed under different temperatures. The ideality factor (n) and barrier height (φ_B) of the heterojunction diode at room temperature (300 K) are found to be 1.28 and 0.43 eV, respectively. Possible conduction mechanisms are examined using various plotting and curve fitting methods for space charge limited conduction mechanism (SCLC), Schottky emission mechanism and Poole-Frenkel (PF) emission mechanism. The heterostructure device shows best fit of SCLC process as compared to the other mechanisms including Schottky emission and PF emission.