Kumar, Pankaj and Jain, S. C. and Kumar, Vikram and Chand, Suresh and Tandon, R. P.
(2008)
Trap filled limit and high currentvoltage characteristics of organic diodes with nonzero Schottky barrier.
Journal of Physics D: Applied Physics, 41 (15).
pp. 1551081.
ISSN 13616463
Abstract
The analytical expressions for trap filled limit voltage (VTFL') and current  voltage characteristics for non zero organic Schottky barrier are derived theoretically. The theoretical results are validated experimentally. In this case, the injected free charge carrier density at the contact is not infinitely large but a finite number p(0). For an exponential distribution of traps the maximum possible number of traps that can be filled in a sample is Hb' = Hb((p(0)/Nupsilon))(1/l), where l = Tc/T, Tc is the characteristic temperature of trap distribution. The use of Fermi  Dirac statistics causes a maximum error of only 6.9% in Hb'.The analytical expression for VTFL' is shown to be VTFL' = 0.5qH(b)'d(2)/epsilon epsilon(0), where d is the sample thickness. As the applied voltage increases and if p(0) > Hb', V2 law is obtained over a considerable range of applied voltage. However, the curves change to Ohm's law as the voltage increases beyond this range. If p(0) < Hb', V2 law is not obtained and the curves directly go to Ohm's law. Experimental results of ITO/PEDOT : PSS/poly(2methoxy52ethyhexyloxy) 1,4phenylenevinylene)(MEHPPV)/Au and ITO/PEDOT : PSS/poly(3hexylthiophene)(P3HT)/Au Schottky diodes are reported. The experimental results show excellent agreement with the theory.
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