Elastic and inelastic tunneling through polyimide LB films

The electron transport mechanism through polyimide (PI) Langmuir-Blodgett (LB) films, with monolayer thickness of 0.4 nm, was investigated by means of current-voltage (I-V) measurement and Inelastic Electron Tunneling Spectroscopy (IETS). Tunnel junctions with a structure of Au/PI/Pb were examined. It was found that electrons tunnel across the PI LB films without loss of their own energy. Tunnel junctions with a PORPI monolayer sandwiched between PI layers were also examined. Here PORPI is polyimide containing tetraphenylporphyrin moiety. It was found that electrons tunnel across the junctions, accompanying the energy loss due to the excitation of vibrational modes of PORPI molecules and the excitation of electron transitions in PORPI molecules