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nanotimes
10-02 :: February 2010
News in Brief
Electronics //
Field-effect-tuned Lateral Organic Diodes
U
sing a unique fluorinated barrier layer-based
lithographic technique, researchers from the
Johns Hopkins University, USA, fabricated a lateral
organic p-n junction, allowing the first observation of
the potential at an organic p-n interface simultane-
ously with the charge transport measurements.
They find that the diode characteristics of the device
(current output and rectification ratio) are consistent
with the changes in the surface potentials near the
junction, and the current-voltage curves and junction
potentials are strongly and self-consistently modula-
ted by a third, gate electrode. The generality of their
technique makes this an attractive method to investi-
gate the physics of organic semiconductor junctions.
© PNAS The values of diode ideality factors (P3 and P4) using
the data fitting model turn out to be two orders of
magnitude higher than their usual values. This is be-
Bal Mukund Dhara, Geetha S. Kinib, Guoqiang Xiab, Byung cause most of the total voltage drop of 60 V (“x/q” in
Jun Junga, Nina Markovicb, and Howard E. Katza: Field- the model equation) occurs across series resistances
effect-tuned lateral organic diodes, In: PNAS Early Edition, on both sides of the junction, as opposed to the 1–2
February 16, 2010, DOI:10.1073/pnas.0910554107: V drop across the junction itself. The next section

http://dx.doi.org/10.1073/pnas.0910554107 shows the voltage drop in the device be- cause of
the series resistances calculated empirically from I–V
data of individual films for two gate bias cases.
© PNAS / Johns Hopkins University