Electrical properties of MIM junctions with ultra-thin polyimide Langmuir-Blodgett films

The electrical properties of metal insulator metal (MIM) junctions with an ultrathin polyimide (PI) Langmuir-Blodgett (LB) film are examined at a temperature from 20 to 300 K. For Al/PI/Al junctions, native aluminum oxide makes a significant contribution to the electrical resistance of Al/PI/Al junctions with an electrical resistance as high as 10⁹ Ω mm², even when the number of deposited layers is zero. For Au/PI/Au junctions, the I-V characteristic shows the existence of metallic pathways when the number of deposited layers n is <30, while the I- V characteristic shows the electrical conduction mechanism ruled by the tunneling theory when n is ⩾30. From the experimental results, it is concluded that PI ultrathin LB films become good electrical insulating barriers when the deposited LB films have a thickness of more than 12 nm. Breakdown voltage of the PI layers sandwiched between both aluminum electrodes and gold electrodes are also investigated