Understanding of the Switching Mechanism of a Pt/Ni-Doped SrTiO₃ Junction via Current–Voltage and Capacitance–Voltage Measurements

Abstract

Following from our work on triply excited hollow resonances in threeelectron atomic systems, a density functional theory (DFT)-based formalism is employed to investigate similar resonances in the Li-isoelectronic series (Z = 4-10). A combination of the work-function-based local nonvariational exchange potential and the popular gradient plus Laplacian-included Lee-Yang-Parr correlation energy functional is used. The generalized pseudospectral method provides nonuniform and optimal spatial discretization of the radial Kohn-Sham equation. First, all the eight n = 2 intrashell states of B 2+ , N 4+ and F 6+ are presented, which are relatively less studied in the literature compared to the remaining four members. Then calculations are performed for the eight 2l2l nl (3 n 6) hollow resonance series, namely 2s 2 ns 2 S e , 2s 2 np 2 P o , 2s 2 nd 2 D e , 2s2pns 4 P o , 2s2pnp 4 D e , 2p 2 ns 4 P e , 2p 2 np 4 D o and 2p 2 ns 2 D e , of all the seven positive ions. Next, as an illustration, higher resonance positions of the 2s 2 ns 2 S e series are calculated for all the ions with a maximum of n = 25. The calculated excitation energies are in excellent agreement with the available literature data (for the n = 2 intrashell states the deviation is within 0.125% and excepting only one case, the same for the resonance series is well below 0.5%). With an increase in Z, the deviations tend to decrease. Radial densities are also presented for some of the selected states. The only result available in the literature for the lower resonances (corresponding to a maximum of n = 17) have been reported very recently. The n > 16 (17 for F 6+ ) resonances are examined here for the first time. This gives a promising viable and general DFT scheme for the accurate calculation of these and other hollow resonances in many-electron atoms.

The role of ion transport phenomena in memristive double barrier devices

“…[?, 13,14] The second hypothesis is that the motion of charged point defects within a sufficiently high applied electric field controls the properties of the tunnel barrier, and therefore the resistance of the device. [15,16] The aim of this work is to provide a model which allows to investigate the role of the ion transport for the resistive switching of the double barrier memristive device. We utilize a 3D kinetic Monte Carlo code in order to describe the ion transport within the solid state electrolyte subject to both externally applied and Coulomb fields.…”

“…To explain the physics two hypotheses are proposed: The first assumes charging and de-charging of trap states within the solid state electrolyte and/or at the metal-semiconductor interface to be the main reason for the resistance change 13 14 15 . The second hypothesis is that the motion of charged point defects within a sufficiently high applied electric field controls the properties of the tunnel barrier as well as the Schottky barrier, and therefore the resistance of the device 16 17 .…”

Cluster-like resistive switching of SrTiO3:Nb surface layers

“…Here, pentavalent Nb is used as a donor for SrTiO 3 substituting the tetravalent Ti. Although after this doping the crystal should be metallic at low carrier concentrations [5,6], surprisingly, resistive switching can be observed in Nb-doped SrTiO 3 thin films [7] and even in single crystals [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], although the nature of the switching process is still under discussion (for details see supplement). Furthermore, a highly resistive surface layer, which arises as soon as the crystal comes into contact with oxygen, was detected on SrTiO 3 :Nb influencing the properties of the whole sample [27,28].…”

Role of Defects and Power Dissipation on Ferroelectric Memristive Switching

“…The most common RS processes related to electronic and electrostatic mechanisms are charge (electrons) trapping/detrapping [ 26 ] and tunneling at the interface. [ 27 ] The dynamics of space‐charges resulted from trapping/detrapping of carriers can modulate SBH and lead to a hysteresis current versus voltage ( I–V ) characteristic, as observed in Pt/Nb:SrTiO 3 /Pt structure. [ 27 ]…”

“…The most common RS processes related to electronic and electrostatic mechanisms are charge (electrons) trapping/ detrapping [26] and tunneling at the interface. [27] The dynamics of space-charges resulted from trapping/detrapping of carriers can modulate SBH and lead to a hysteresis current versus voltage (I-V) characteristic, as observed in Pt/Nb:SrTiO 3 /Pt structure. [27] Ferroelectric materials, which also give rise to interfacetype switching, have been explored for potential applications in ReRAM in two ways: a) ferroelectric diodes (FeDs), where the spontaneous polarization can be switched by applying an E field of opposite polarity and such a polarization switching can modulate the SBH [28] and therefore the conduction, and b) ferroelectric tunnel junction, where the tunnel junction barrier can be modified.…”