Excimer laser induced permanent electrical conductivity and nanostructures in polymers.

摘要

The electrical conductivity of high temperature polymers (i.e. polyimide) has been changed permanently from 10(sup (minus)17) (Omega)(sup (minus)1) cm(sup (minus)1) to 10 (Omega)(sup (minus)1) cm(sup (minus)1) by KrF (248 nm) excimer laser irradiation. The conduction mechanism is found to be phonon assisted variable range hopping between small ((approximately)10 nm) carbon rich clusters that form a macroscopic percolation cluster. Using a holographic technique, periodic line structures with periods ranging from 166 mn to 950 nm have been produced in polyimide by direct ablation with a KrF excimer laser. Taking advantage of the large nonlinearity in the laser ablation process, linewidths ranging from 30 mn to several hundred nm could be obtained. This technique was combined with the ability to induce electrical conductivity in polyimide to produce an array of 500 mn wide electrically conducting wires. The conductivity of these wires was similar to that found in macroscopic regions of laser induced conductivity.