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Durham University

Department of Engineering

Staff Profile

Publication details for Professor Dagou Zeze

Dimitrakis, P, Normand, P, Tsoukalas, D, Pearson, C, Ahn, JH, Mabrook, MF, Zeze, DA, Petty, MC, Kamtekar, KT, Wang, CS, Bryce, MR & Green, M (2008). Electrical behavior of memory devices based on fluorene-containing organic thin films. Journal of Applied Physics 104(4): 044510.

Author(s) from Durham

Abstract

We report on switching and negative differential resistance (NDR)
behaviors of crossed bar electrode structures based on Al/organic
layer/Al devices in which the organic layer was a spin-coated layer of
7-{4-[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]phenyl}-9,9-dihexyl-N,
N-diphenyl-fluoren-2-amine. The addition of gold nanoparticles (0.5 wt
%) did not change the switching behavior of thicker film structures;
however, devices incorporating the nanoparticles showed more
reproducible characteristics. In most cases, a "forming" process, in
which a large positive voltage was applied to the top Al electrode, was
required before the NDR and conductivity switching were observed. Three
different electrical conductivity mechanisms have been identified:
Poole-Fretikel conductivity in unformed structures, linear current
versus voltage characteristics for the ON state in formed devices, and
superlinear current versus voltage behavior for the OFF state in formed
devices. Models based on metallic filaments or on the injection and
storage of charge do not explain all our experimental observations
satisfactorily. Instead, an explanation based on the formation of
nanocrystalline regions within the thin film is suggested. The devices
can be used as two-terminal memory cells operating with unipolar
voltage pulses. (C) 2008 American Institute of Physics.