Hole transport in corona-charged 12 μm Sheldahl FEP samples interpreted through a field-dependent schubweg model

Potential build up and decay curves for positive corona-charged 12 μm Sheldahl FEP foils are measured and best interpreted using the conventional field dependent schubweg and a trap structure as follows: shallow traps at the polymer surface (mean life time of 103 s) and quasi-deep traps (mean detrapping time of 7 × 103 s) in the bulk. For this trap, only the product of the mobility by the trapping time is relevant (of the order of 10−10 cm2/V). Comparison between measurements in pure N2 dry air, and ambient air demonstrates that moisture has a not negligible effect on the charge transport, decreasing the surface potential. Evidence is obtained that holes trapped at the surface are located a little beneath the polymer surface confirming previous measurement by von Seggern through heat pulse technique.