Percolative Metal-Insulator Transition in Excimer Laser Irradiated Polyimide

Abstract

The metal-insulator transition observed in excimer laser irradiated polyimide is presented as a new experimental method to study three-dimensional percolation. The conductivity critical exponent $t$ and the percolation threshold ${\ensuremath{\Phi}}_{c}$ are measured in situ for the transition under both Ohmic and non-Ohmic conditions. The experimental values obtained in the Ohmic case were ${\ensuremath{\Phi}}_{c}=0.31\ifmmode\pm\else\textpm\fi{}0.06$ and $t=2.00\ifmmode\pm\else\textpm\fi{}0.05$. These values are in close agreement with theory. The dependence of the critical exponent on current voltage characteristics of conducting sites is demonstrated for the first time.