Analysis of Potential Distribution and Current–Voltage Characteristic in Polyimide Langmuir–Blodgett Films

• Published in: Japanese Journal of Applied Physics Vol. 40; no. 7R; p. 4575
• Main Authors: Li, Cheng-Quan, Noguchi, Yutaka, Wu, Hong-Cai, Iwamoto, Mitsumasa
• Format: Journal Article
• Language: English
• Published: 01.07.2001
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.40.4575

The current–voltage ( I – V ) characteristics of Au electrode (M)–polyimide (PI) Langmuir–Blodgett (LB) film (I)–Al electrode (M)-MIM element are analyzed, taking into account the interfacial electrostatic phenomena and the presence of the interfacial electronic states. On the basis of the Richardson–Schottky model, the attractive force and potential energy created by a series of mirror image charges against both electrodes are calculated. A positive bias ( V ex >0) applied to an Au–PI LB film–Al element gives rise to the injection of electrons from the Au electrode into the lowest unoccupied molecular orbitals (LUMO) of PI LB film, whereas a negative bias ( V ex <0) causes the injection from Al electrode. The potential distributions across the PI LB film and the potential barrier height under the condition of various externally applied voltages ( V ex ) are calculated, assuming the presence of surface states at the metal/film interface. It is determined that the calculation results of the I – V characteristics can predict the experimental results.