Electrical behaviour of discontinuous silver films deposited on compatible Polystyrene/Poly (2-vinylpyridine) composite

Polystyrene (PS) and Poly (2-vinylpyridine) (P2VP) was melt blended. The compatibility of PS/P2VP was investigated by differential scanning calorimetry (DSC), Fourier transmission Infrared (FTIR) and scanning electron microscopy (SEM). The results indicated the single glass transition temperature for the blend. Results of the studies carried out on the electrical behaviour of silver island films deposited on the composite of PS and P2VP are presented here. The substrates were held at 457 K, much above the glass transition temperature of the polymers to ensure sufficient polymer fluidity during deposition, to obtain a sub-surface particulate film. A constant deposition rate of 0.4 nm/s was used through out the study. Silver films deposited on softened PS give rise to a very high room temperature resistance approaching that of the substrate resistance due to the formation of a highly agglomerated structure. On the other hand, films on softened P2VP gives rise to a room temperature resistance in the range of tens to a few hundred MΩ/□ which is desirable for device applications. The composite of PS and P2VP show resistances at room temperature. The films show an increase in resistance, when they are exposed to atmosphere. This is attributed to the oxidation of silver islands. The film resistances in the desired range could be obtained even, after exposure to atmosphere with PS concentration of 50%.