Investigation of schottky barrier of poly(phenyl azo methane thiophene) using current–voltage and impedance spectroscopy

Current–voltage, impedance spectroscopy and capacitance–voltage characteristics have been carried out on indium tin oxide (ITO)/poly(phenyl azo methane thiophene) (PPAT)/In schottky barrier device. In this device, injection and transport is expected to be dominated by holes. The conduction mechanism in low field region is ohmic whereas the space charge limited current theory with an exponential distribution of traps is in extremely good agreement with at higher voltage region. The characteristic energy (Et) of the exponential traps distribution is 0.13 eV from the valence band edge at room temperature but this shifts towards the valence band edge with the increase in temperature. Electrical impedance measurements on PPAT schottky barrier diodes in the frequency range 40 Hz–100 kHz were also reported. The device having configuration ITO/PPAT/In display the schottky behaviour, which can be modelled by a simple equivalent circuit of two RC elements in series, representing a bulk and a junction region. Low frequency device capacitance shows a pronounced voltage dependence and from a detailed analysis, the ionised acceptor concentration, potential barrier height and width of depletion layer have been calculated and discussed in detail.