Liquid-metal ion sources inducing conductivity in polyimide

Modification of electrical conductivity in polyimide by ion irradiation has been studied in a large range of ion fluence (0-5 × 1017 cm-2), with respect to the ion fluence rate (0.3 × 1013 -2.2 × 1014 cm-2s-1). The investigated energy range concerns the medium energy (10-240 keV). Whatever the ion fluence rate, there is a threshold like dependence upon the ion fluence for which the conductivity climbs to a maximum and constant value. For classical fluence rates, around 1013 cm-2s-1, the conductivity limit does not exceed 10-1 S cm1, and is strongly dependent on the electronic stopping power of the implanted ion. It is always accompanied by a notable shrinkage. At higher fluence-rate (#1014 cm-2s-1) obtained by a liquid-metal ion source, a conductivity of 300 S cm-1 has been reached without measurable shrinkage.