Effect of interface geometry on electron tunnelling in Al/Al<sub>2</sub>O<sub>3</sub>/Al junctions

Koberidze, M.; Feshchenko, A. V.; Puska, Martti J.; Nieminen, R.M.; Pekola, Jukka P.

doi:10.1088/0022-3727/49/16/165303

Cited by 13 publications

(15 citation statements)

References 32 publications

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“…In our previous 2469-9950/2018/97(19)/195406 (11) 195406-1 ©2018 American Physical Society study [6], we demonstrated the effect of the different interface structures on the tunnel barrier heights and widths for the Al/Al 2 O 3 /Al tunnel junctions. The work was based on the analysis of experimental current-voltage (I V ) data using analytic models for tunneling current, where the employed barrier parameters were those predicted by DFT.…”

Section: Introductionmentioning

confidence: 73%

“…Barrier parameters for the Al/Al 2 O 3 interfaces from Ref. [6]. φ is the barrier height, s is the width of the transition region, and s is the width of the barrier.…”

Section: Atomic Relaxations At the Al/α-al 2 O 3 Interfacesmentioning

confidence: 99%

“…s is the width of the barrier from Ref. [6]. Interplanar relaxations in the metal parts are illustrated in Figs.…”

Section: E Interlayer Relaxations In Al/α-al 2 O 3 Systemsmentioning

confidence: 99%

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Structural details of Al/Al2O3 junctions and their role in the formation of electron tunnel barriers

2018

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We present a computational study of the adhesive and structural properties of the Al/Al 2 O 3 interfaces as building blocks of the metal-insulator-metal (MIM) tunnel devices, where electron transport is accomplished via tunneling mechanism through the sandwiched insulating barrier. The main goal of this paper is to understand, on the atomic scale, the role of the geometrical details in the formation of the tunnel barrier profiles. Initially, we concentrate on the adhesive properties of the interfaces. To provide reliable results, we carefully assess the accuracy of the traditional methods used to examine Al/Al 2 O 3 systems. These are the most widely employed exchangecorrelation functionals-local-density approximation and two different generalized gradient approximations; the universal binding-energy relation for predicting equilibrium interfacial distances and adhesion energies; and the ideal work of separation as a measure of junction stability. In addition, we show that the established interpretation of the computed ideal work of separation might be misleading in predicting the optimal interface structures. Finally, we perform a detailed analysis of the atomic and interplanar relaxations in each junction, and identify their contributions to the tunnel barrier parameters. Our results imply that the structural irregularities on the surface of the Al film have a significant contribution to lowering the tunnel barrier height, while atomic relaxations at the interface and interplanar relaxations in Al 2 O 3 may considerably change the width of the barrier and, thus, distort its uniformity. Both the effects may critically influence the performance of the MIM tunnel devices.

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Section: Introductionmentioning

confidence: 73%

“…Barrier parameters for the Al/Al 2 O 3 interfaces from Ref. [6]. φ is the barrier height, s is the width of the transition region, and s is the width of the barrier.…”

Section: Atomic Relaxations At the Al/α-al 2 O 3 Interfacesmentioning

confidence: 99%

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Structural details of Al/Al2O3 junctions and their role in the formation of electron tunnel barriers

2018

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“…1 Since the definition is based on homogeneous bulk parameter values of different constituents, it does not account for the interface effects that can have a significant influence on the height of the barrier as shown in a recent study on Al/Al 2 O 3 /Al systems. 38 Depending on the structure, metal states can penetrate into the insulator forming the so-called metal-induced gap states (MIGS), lowering the barrier height. 39 In addition, barrier properties such as ferroelectricity may cause accumulation of charge and induce screening effects, which alter the barrier height and shape.…”

Section: A Barrier Parametersmentioning

confidence: 99%

Modeling of electron tunneling through a tilted potential barrier

Tuomisto

Zugarramurdi

Puska

2017

Journal of Applied Physics

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“…Here, c is the length of one period. For LCMO and SFMO slabs, the respective lattice parameters are taken as c. In the case of superlattice, the V M A is calculated using the c lattice parameter of SFMO as well as that of LCMO and the average of the two is considered to minimize the error at the interface [40]. When compared with the vacuum level, the V M A of the SFMO slab is found to be ∼ 1 eV higher than that of the LCMO side.…”

Section: Formation Of Periodic Quantum Well Structurementioning

confidence: 99%

Quantum well structure of a double perovskite superlattice and formation of a spin-polarized two-dimensional electron gas

2018

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Layered oxide heterostructures are the new routes to tailor desired electronic and magnetic phases emerging from competing interactions involving strong correlation, orbital hopping, tunnelling and lattice coupling phenomena. Here, we propose a half-metal/insulator superlattice that intrinsically forms spin-polarized two-dimensional electron gas (2DEG) following a mechanism very different from the widely reported 2DEG at the single perovskite polar interfaces. From DFT+U study on Sr2FeMoO6/La2CoMnO6 (001) superlattice, we find that a periodic quantum well is created along [001] which breaks the three-fold t2g degeneracy to separate the doubly degenerate xz and yz states from the planar xy state. In the spin-down channel, the dual effect of quantum confinement and strong correlation localizes the degenerate states, whereas the dispersive xy state forms the 2DEG which is robust against perturbations to the superlattice symmetry. The spin-up channel retains the bulk insulating. Both spin polarization and orbital polarization make the superlattice ideal for spintronic and orbitronic applications. The suggested 2DEG mechanism widens the scope of fabricating next generation of oxide heterostructures. arXiv:1805.06128v2 [cond-mat.str-el]

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Effect of interface geometry on electron tunnelling in Al/Al₂O₃/Al junctions

Cited by 13 publications

References 32 publications

Structural details of Al/Al2O3 junctions and their role in the formation of electron tunnel barriers

Structural details of Al/Al2O3 junctions and their role in the formation of electron tunnel barriers

Modeling of electron tunneling through a tilted potential barrier

Quantum well structure of a double perovskite superlattice and formation of a spin-polarized two-dimensional electron gas

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Effect of interface geometry on electron tunnelling in Al/Al2O3/Al junctions

Cited by 13 publications

References 32 publications

Structural details of Al/Al2O3 junctions and their role in the formation of electron tunnel barriers

Structural details of Al/Al2O3 junctions and their role in the formation of electron tunnel barriers

Modeling of electron tunneling through a tilted potential barrier

Quantum well structure of a double perovskite superlattice and formation of a spin-polarized two-dimensional electron gas

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Effect of interface geometry on electron tunnelling in Al/Al₂O₃/Al junctions