Negative charge transport in FEP by constant current method

Using the constant current triode
^1,2
, we have been able to inject negative carriers in 12µm Teflon FEP foils, when the deposited charge density surpassed 2,3×10
⁻⁷
C/cm
²
(corresponding to 1,1 MV/cm). This is shown in curve I Fig.1. Initially the surface potential increases linearly with time. The linear behavior lasts until the voltage reaches a value of approximately 1400V. The subsequent sublinear growth of voltage with time indicates charge injection. We have verified that no potential decay is observed if the corona is cut off before the potential reaches V
s
, in dependently of the charging current I
0
. For long charging times, the voltage reaches a stationary value.