Journal Article

PreJuSER-49730

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Theoretical current-voltage characteristics of ferroelectric tunnel junctions

Kohlstedt, H.FZJ* ; Pertsev, N. A.FZJ* ; Contreras, J. R.FZJ* ; Waser, R.FZJ*

2005
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/1017  doi:10.1103/PhysRevB.72.125341

Abstract: We present the concept of ferroelectric tunnel junctions (FTJs). These junctions consist of two metal electrodes separated by a nanometer-thick ferroelectric barrier. The current-voltage characteristics of FTJs are analyzed under the assumption that the direct electron tunneling represents the dominant conduction mechanism. First, the influence of converse piezoelectric effect inherent in ferroelectric materials on the tunnel current is described. The calculations show that the lattice strains of piezoelectric origin modify the current-voltage relationship owing to strain-induced changes of the barrier thickness, electron effective mass, and position of the conduction-band edge. Remarkably, the conductance minimum becomes shifted from zero voltage due to the piezoelectric effect, and a strain-related resistive switching takes place after the polarization reversal in a ferroelectric barrier. Second, we analyze the influence of an internal electric field arising due to imperfect screening of polarization charges by electrons in metal electrodes. It is shown that, for asymmetric FTJs, this depolarizing-field effect also leads to a considerable change of the barrier resistance after the polarization reversal. However, the symmetry of the resulting current-voltage loop is different from that characteristic of the strain-related resistive switching. The crossover from one to another type of the hysteretic curve, which accompanies the increase of FTJ asymmetry, is described taking into account both the strain and depolarizing-field effects. It is noted that asymmetric FTJs with dissimilar top and bottom electrodes are preferable for the nonvolatile memory applications because of a larger resistance on/off ratio.

Keyword(s): J

Note: Record converted from VDB: 12.11.2012

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Contributing Institute(s):

1. Elektronische Materialien (IFF-IEM)
2. Center of Nanoelectronic Systems for Information Technology (CNI)

Research Program(s):

1. Materialien, Prozesse und Bauelemente für die Mikro- und Nanoelektronik (I01)

Appears in the scientific report 2005
Notes: This version is available at the following Publisher URL: http://prb.aps.org

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