Fabrication and Characterization of Schottky Junctions of Aluminum with Polyaniline Containing Hydrolysis Products

Schottky diodes based on Al/polyaniline ~PANI!, electrodeposited by cyclic voltammetry ~CV! with two different upper oxidation potentials, 0.8 and 1.1 V, respectively, were fabricated. Auger electron spectroscopy ~AES! confirms the presence of hydrolysis products of PANI, benzoquinone ~BQ!/hydroquinone ~HQ! for PANI film deposited with a switch potential of 1.1 V. The electrical properties of the Al/PANI ~with inbuilt hydrolysis products! and Al/PANI ~without hydrolysis products! junctions were evaluated at different temperatures by current-voltage characteristics and impedance spectroscopy measurements. The presence of inbuilt hydrolysis products with PANI influences the electrical properties of the junction. The junctions were found to be rectifying in both cases but with wide differences in junction parameters, such as barrier height, ideality factor, and saturation current density, between them. The temperature dependence of the impedance spectra of the devices was found to have variations. Impedance parameters of the devices were deduced from a proposed equivalent circuit. The combined analyses of current-voltage characteristics and impedance measurements reveal that the presence of hydrolysis products with PANI in Al/PANI junction increases the contact resistance, depletion layer thickness, and barrier height of the device.