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Top: Layout of the capacitor and the schematic flat band diagram for the dielectric layers. Bottom: The voltage across the capacitor as function of time under CCS of 1 μA/cm2. An abrupt voltage drop is observed when voltage reaches 10 V. Inset shows the corresponding change in capacitance estimated from the change in slope of the voltage.
(a) Current decay as function of time with different voltage biases (0.5–5 V) applied after the diode is electroformed by CCS. The current is measured at 0.5 V. The inset shows that the power law (α) of current decay is directly proportional to the electric field. (b) Thickness dependence of current degradation monitored by voltage ramp (1 V) after forming by CCS, respectively.
After electroforming performed with CCS (1 μA), (a) curve shows no current degradation with an illumination (1000 s) of a blue LED applied shortly after the electroforming. The current decay (at t = 25 h) restarts when a voltage ramp (0–5 V) is introduced. (b) The line shows the power law of current decay after electroforming, when the diode is kept in the dark and short-circuited. To minimize the effect of the applied bias the current decay was monitored at 0.5 V.
(a) Injection and trapping of electrons at the oxide/polymer interface. (b) Injection and trapping of holes into the oxide. Trapped holes are stabilized by the presence of electrons (dipole layer). (c) Dissociation of the dipole layer caused by recombination. (d) Trapped electrons are removed by illumination the polymer layer with photons having energy larger than the band-gap of the polymer.
(a) Schematic representation of the capacitor as a three layer electrostatic system with the oxide, the double layer, and the polymer layer. d ox, d dl, d pol and ε ox, ε dl, ε pol represent the thicknesses and the dielectric constants, respectively. Number of trapped holes in the oxide p versus time as predicted by Eq. (7) for different bias voltages (b) and different oxide thickness (c). The current is expected to be proportional to the number of trapped holes.
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