Electrical transport properties of polyimide Langmuir-Blodgett films incorporating MIS junctions fabricated by the LB technique

The authors fabricated metal-insulator-semiconductor (MIS) junctions having a structure of Au/polymide (PI)/squarylium-dye-arachidic(SQ-C20) mixed system by the Langmuir-Blodgett (LB) technique, and then examined the electrical transport properties of the junctions. It was found that a PI LB film becomes a good electrical insulator even when the number of deposited layers is five. From capacitance-voltage (C-V) measurement, it was found that a SQ-C20 multilayered film is depleted at the interface between the PI layer and the SQ-C20 layer even when the biasing voltage was zero millivolts, because positive excess charges are displaced from the gate-Au electrode to the PI layer as deposited. The PI layer incorporated in the junctions makes a significant contribution to the electrical conduction, and asymmetric current-voltage (I-V) characteristics were obtained for the junctions