Impact of applied strain on the electron transport through ferroelectric tunnel junctions

State and Key Laboratory of Optoelectronic Materials and Technologies, Institute of Optoelectronic and Functional Composite Materials, and School of Physics and Engineering, Sun Yat-sen University, 510275 Guangzhou, People's Republic of China
Applied Physics Letters (Impact Factor: 3.52). 08/2010; 97(1):012905 - 012905-3. DOI: 10.1063/1.3462070
Source: IEEE Xplore

ABSTRACT Combining nonequilibrium Green’s functions with density-functional theory, we have investigated the effect of external strain field on the tunneling electroresistance (TER) of ferroelectric material sandwiched between Pt electrodes. The results show that the strain induced para/ferroelectric phase transitions play an important role in the electronic transport properties of the junction. Sizable enhancements in the resistance are found for the strained ferroelectric junctions with a TER ratio of 9000%. Detail analyses show that the Ti–O displacements along the transport direction in ferroelectric barrier change the effective potential profile, resulting in a giant piezoelectric resistance in the ferroelectric tunnel junctions.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Electronic tunneling through ferroelectric insulators is considered to be a key ingredient of future oxide electronics. We investigate the role of the electronic band structure of the decaying electronic states in the band gap by first discussing the expected behavior of tunneling in the effective mass model. We demonstrate that, even for the simple prototype ferroelectric oxides in the perovskite structures PbTiO3 and BaTiO3, the basic assumption of the effective mass model is not appropriate, and that the correct interpretation of tunneling in these materials requires a material-specific description of the evanescent states as provided by the complex band structure.
    Physical review. B, Condensed matter 04/2011; 83(15). DOI:10.1103/PhysRevB.83.155114 · 3.66 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Based on the first principles simulations and quantum transport calculations, effects of dissimilar electrodes and interfaces on the current transport and relevant electrical properties in ZnO tunnel junctions as well as the mechanism of current asymmetric characteristic adjustment have been investigated. Our results show that the potential energy, built-in electric field, electron transmission probability, current, etc. in ZnO tunnel junctions can be tailored by adopting asymmetric electrode combinations. By adopting dissimilar electrodes to fabricate different potential barriers, we have performed manipulations on current transport in ZnO tunnel junctions and realized the enhancement and even the reversal of the current asymmetric characteristic. We also demonstrate that it is the different potential energy levels of the dissimilar electrodes in asymmetric tunnel junctions playing an important role in the adjustment of current asymmetry, which is innovative and different from the mechanism of current asymmetry adjustment through strain-induced piezopotential reversal. This investigation exhibits a novel and significant method for controlling or modifying the performances of electronic devices by utilizing dissimilar electrodes.
    Journal of Applied Physics 07/2013; 114(4). DOI:10.1063/1.4816796 · 2.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Critical properties, such as the phase transition temperature, critical thickness and Curie–Weiss-type relation, of nanoscale asymmetric ferroelectric tunnel junctions or capacitors are investigated, considering the effects of size, surfaces, asymmetric interfaces and electrodes on the stability and magnitude of the two spontaneous polarization states. Using the modified thermodynamic model and taking into account contributions of the depolarization field, built-in electric field, interface and surface energies to the thermodynamic potential, explicit expressions of the critical properties are derived. For the asymmetric ferroelectric tunnel junction or capacitor, the results illustrate two important behaviors of vanishing critical thickness for the spontaneous polarization and smearing of the phase transitions, respectively. In addition, other critical properties are discussed as functions of the ambient temperature, misfit strain, surface coefficients, work function steps, dielectric constants and screening lengths of electrodes. Owing to the high-sensitivity of the critical properties to structures of asymmetric interfaces and electrodes, the results also suggest that the critical and other functional properties of nanoscale asymmetric ferroelectric tunnel junctions or capacitors can be completely controlled by adjusting the difference between asymmetric interfaces or electrodes.
    Acta Materialia 02/2012; 60(4):1857–1870. DOI:10.1016/j.actamat.2011.12.048 · 3.94 Impact Factor


Available from
Dec 20, 2014