Electrical breakdown of ultra-thin polyimide Langmuir-Blodgett films under a needle-plane electrode system

Electrostatic phenomena occurring at insulator-metal interfaces are interesting to the fields of electronics. In this study, we examined the surface potential of electrical insulating polyimide (PI) Langmuir-Blodgett (LB) films on metal (Al and Au) electrodes, which were charged at various voltages under a needle-plane electrode system. PI LB films were negatively charged as the biasing voltage applied to the needle-electrode increased. The surface potential saturated when the number of deposited layers was 20-30, and it was dependent on the nature of metal electrode. The interfacial electrostatic space charge at the as-deposited film/metal interface made a significant contribution to the dielectric breakdown of ultra-thin films. As a result, PI LB films deposited on Al electrode were broken at lower voltage than that on Au electrode. (C) 2003 Elsevier Science B.V. All rights reserved.