Determining the Efficiency of Fast Ultrahigh-density Writing of Low-Conductivity Patterns on Semiconducting Polymers
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Determining the Efficiency of Fast Ultrahigh-density Writing of Low-Conductivity Patterns on Semiconducting Polymers Panagiotis E. Keivanidis1*, Andrea di Donato2, Davide Mencarelli2, Alessandro Esposito2 ,Tengling Ye3, Guglielmo Lanzani3, Giuseppe Venanzoni2, Tiziana Pietrangelo4, Antonio Morini2, Marco Farina2 1
Cyprus University of Technology, Department of Mechanical Engineering and Materials Science and Engineering, Limassol, Cyprus 2 Department of Information Engineering, Universita` Politecnica delle Marche, Ancona, Italy. 3 CNST of IIT@POLIMI, Milano, Italy 4 Department of Neuroscience and Imaging, Universita` ‘G. d’Annunzio’, Chieti, Italy. ABSTRACT We present a nano-patterning process for semiconducting polymeric composites that could potentially be utilized for the development of polymer-based data storage devices. Nanopatterning (writing) operates on the basis of the mechanical interaction between the electrically unbiased tip of an atomic force microscope and the surface of polymeric composite films. Via friction forces, the tip/sample interaction produces a local increase of molecular disorder in the polymer matrix, inducing a localized lowering in the conductivity of the organic semiconductor. Herein we suggest a figure of merit for quantifying the efficiency of pattern formation and we address the dependence of the writing process on the thermal annealing temperature of the composite film. Control experiments on composite films deposited on substrates with different roughness suggest that the writing effect is invariant to the roughness of the substrate. The potential storage density of the writing process depends on the tip curvature. INTRODUCTION The realization of high-density, low-cost storage media of high longevity can be enabled by the technological development of programmable and readable nonvolatile organic memory devices. Amid the ongoing efforts for the development of high density nonvolatile memory systems [1] the use of scanning probe techniques [2] has emerged as a promising concept for the realization of high capacity and storage density memory devices. Here we show that the mechanical interaction between the electrically unbiased tip of the atomic force microscope and the surface of π-conjugated polymeric films produces a local increase of molecular disorder, inducing a localized lowering of the semiconductor conductivity, not associated to detectable modifications in the surface topography [3]. This phenomenon allows for the swift production of low-conductivity patterns on the film surface at a speed exceeding 20 μm/s; the patterned paths have a resolution in the order of the tip size (20 nm) and they are clearly detectable in the conductivity maps, as registered by the conducting-atomic force microscopy (C-AFM) imaging characterization.
EXPERIMENTAL DETAILS Measurements were performed through an atomic force microscope (AFM) NT-MDT Solver Pro P47 on air, equipped with head for conductive, contact, semicontact and tapping measurements. The C-AFM unity (model AU006) allows performi
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