Forming-free bipolar resistive switching in nonstoichiometric ceria films

Abstract

The mechanism of forming-free bipolar resistive switching in a Zr/CeO x /Pt device was investigated. High-resolution transmission electron microscopy and energy-dispersive spectroscopy analysis indicated the formation of a ZrO y layer at the Zr/CeO x interface. X-ray diffraction studies of CeO x films revealed that they consist of nano-polycrystals embedded in a disordered lattice. The observed resistive switching was suggested to be linked with the formation and rupture of conductive filaments constituted by oxygen vacancies in the CeO x film and in the nonstoichiometric ZrO y interfacial layer. X-ray photoelectron spectroscopy study confirmed the presence of oxygen vacancies in both of the said regions. In the low-resistance ON state, the electrical conduction was found to be of ohmic nature, while the high-resistance OFF state was governed by trap-controlled space charge-limited mechanism. The stable resistive switching behavior and long retention times with an acceptable resistance ratio enable the device for its application in future nonvolatile resistive random access memory (RRAM).

Conduction Mechanism of Valence Change Resistive Switching Memory: A Survey

“…However, there are few exceptions, such as [45,46,50,52,53] where only Ohmic conduction is observed in LRS.…”

“…However, there is no I-V 2 region observed in positive-biased LRS as shown in Figure 13, which could be capped by the current compliance imposed on the device. Similarly, for the Zr/CeOx/Pt memory device [52], the Ohmic conduction in LRS can be explained by the current compliance limit in negative voltage region and low Vreset in positive voltage region as shown in Figure 14. Generally, observation of three apparent regions where (i) I ∝ V, (ii) I ∝ V 2 and (iii) steep increase of I, signifies the dominant of SCLC mechanism.…”

“…The I ∝ V 2 region is known as trap-unfilled SCLC region, while the third region is often referred as trap-filled SCLC region. Hence, the probability of SCLC conduction is usually higher if the electrode's contact is highly carrier injective [52]. According to the SCLC theory [83], for the simple case of a single discrete trapping level, the current density at high field is given by Equation (6) [84]:…”

“…While CF evolution is typically associated with thermal, electrical or ion migration [19,20], there is no consensus on the dominant conduction mechanism in resistive switching memory devices [21][22][23]. Among the commonly observed conduction mechanisms are: (i) Poole-Frenkel emission [24][25][26][27][28][29][30][31][32]; (ii) Schottky emission [33][34][35][36][37][38][39][40][41][42]; (iii) SCLC [43][44][45][46][47][48][49][50][51][52][53] (iv) trap-assisted tunneling [54][55][56][57][58][59]; and (v) hopping conduction [60][61][62][63][64][65]. To enhance the device performance and data retention property, it is crucial to identifying t...…”

Development of copper-enriched porous coatings on ternary Ti-Nb-Zr alloy by plasma electrolytic oxidation

“…The XPS spectra were recorded in normal emission. For the XPS analyses, the CasaXPS 2.3.14 software (Shirley background type) [73] with the help of XPS tables [73][74][75][76][77][78][79] was used. All the binding energy values presented in this paper were charge-corrected to C 1s at 284.8 eV.…”