Poole-Frenkel effect and variable-range hopping conduction in metal/YBCO resistive switching devices

Abstract

Current-voltage (IV) characteristics and the temperature dependence of the contact resistance [R(T )] of Au / YBa 2 Cu 3 O 7−δ (optimally doped YBCO) interfaces have been studied at different resistance states. These states were produced by resistive switching after accumulating cyclic electrical pulses of increasing number and voltage amplitude. The IV characteristics and the R(T ) dependence of the different states are consistent with a Poole-Frenkel (P-F) emission mechanism with trapping-energy levels E t in the 0.06-0.11 eV range. E t remains constant up to a number-of-pulsesdependent critical voltage and increases linearly with further increasing the voltage amplitude of the pulses. The observation of a P-F mechanism reveals the existence of an oxygen-depleted layer of YBCO near the interface. A simple electrical transport scenario is discussed, where the degree of disorder, the trap energy level and the temperature range determine an electrical conduction dominated by non-linear effects, either in a P-F emission or in a variable-range hopping regime.

Graphical analysis of current-voltage characteristics in memristive interfaces

“…We may speculate that it can be a consequence of their capacitor-like structure where both a phaseseparated interfacial zone and the proper oxide have a relevant participation in the conducting process. The interfacial zone would be composed by a mixture of conducting and insulating regions [7,12,13], probably associated with a disordered distribution of oxygen vacancies (phase separation), leading to the existence of a non-linear element in parallel with an ohmic one. The series ohmic element would then represent the bulk contribution of the oxide.…”

“…As an example of a device based on an electric-field-trap-controlled SCLC mechanism we can mention Ag/La 0.7 Ca 0.3 MnO 3−δ interfaces [6], while Au/YBa 2 Cu 3 O 7−δ interfaces show a PF conduction in a variable-range hopping scenario, with a pulse-controlled-trap energy level that determines their resistance switching properties. [7] In this way, different scenarios can be considered to explain the microscopic origin of the resistance change of the device, related to the particular choice of materials for the metal/oxide interface. As shown previously [1,2], by using their isothermal IV characteristics that it is possible to distinguish if the conduction of the device is related to an ohmic behavior (I ∼ V ), or a space charge limited conduction (SCLC, I ∼ V 2 ), or a Poole-Frenkel (PF), Fowler-Nordheim (FN) or Schottky (Sch) emissions [I ∼ exp(V n )].…”

Origin of multistate resistive switching in Ti/manganite/SiOx/Si heterostructures

“…It can be found typically in interfaces of metal-complex oxides, like cuprates or cobaltites [39,40]. In this way, its origin can be related to the LCMO layer, which contributes with a pure ohmic conduction in the R HIGH and R LOW regimes, but becomes Poole-Frenkel after the R LOW R INT transition, due to the generation of defects (traps).…”

The Poole-Frenkel laws and a pathway to multi-valued memory

“…We have extracted C F from a number of publications [14][15][16][17][18][19][20][21][22] and found these coefficient varying by approximately one order of magnitude between different cases. Such variations are hardly attributable to the effect of ε, while they can be readily explained by the differences in the disorder parameters V m and a.…”