Threshold Switching in Amorphous Cr-Doped Vanadium Oxide for New Crossbar Selector

Rupp, Jonathan A. J.; Waser, Rainer; Wouters, Dirk J.

doi:10.1109/imw.2016.7495293

Cited by 12 publications

(6 citation statements)

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“…NbO 2 , VO 2 and V 2 O 3 ) undergo thermally-induced insulator metal transitions [13][14][15] and there has been particular interest in understanding if these contribute to the volatile switching characteristics [16,17]. Indeed, it is commonly argued that volatile switching in amorphous NbO x and VO x films is preceded by crystallization of these phases, and that these are responsible for the observed switching [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO _x

Nath

Nandi

et al. 2020

Nanotechnology

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Reactive metal electrodes (Nb, Ti, Cr, Ta, and Hf) are shown to play an important role in controlling the volatile switching characteristics of metal/Nb2O5/Pt devices. In particular, devices are shown to exhibit stable threshold switching under negative bias but to have a response under positive bias that depends on the choice of metal. Three distinct responses are highlighted: Devices with Nb and Ti top electrodes are shown to exhibit stable threshold switching with symmetric characteristics for both positive and negative polarities; devices with Cr top electrodes are shown to exhibit stable threshold switching but with asymmetric hysteresis windows under positive and negative polarities; and devices with Ta and Hf electrodes are shown to exhibit an integrated thresholdmemory (1S1M) response. Based on thermodynamic data and lumped element modelling these effects are attributed to the formation of a metal-oxide interlayer and its response to field-induced oxygen exchange. These results provide important insight into the physical origin of the switching response and pathways for engineering devices with reliable switching characteristics.

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Section: Introductionmentioning

confidence: 99%

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO _x

Nath

Nandi

et al. 2020

Nanotechnology

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“…Therefore, the realization of amorphous Cr-doped V 2 O 3 thin films as "precursor" is a further valuable goal that is of interest e.g. for selector devices [32] [33].…”

Section: Introductionmentioning

confidence: 99%

Competition between V2O3 phases deposited by one-step reactive sputtering process on polycrystalline conducting electrode

et al. 2020

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This comprehensive work investigates a technologically appealing synthesis of V 2 O 3 oxide thin films for electronic applications by the use of direct reactive sputtering with a heavily diluted gas mixture on a conducting platinum electrode. Morphological characterization was performed by Scanning Electron Microscopy, Atomic Force Microscopy , X-Ray Diffraction and X-Ray Reflectometry. Vanadium valence states were investigated by X-Ray Photoelectron Spectroscopy and crystalline phases were checked by X-Ray Grazing Incidence measurements. Low temperature electrical transport characteristics were determined by 2-point probe measurements. Only amorphous V 2 O 3 was found to exist in a mixed-valence phase in the 2 investigated parameter range. Deposition temperatures between 400 °C and 550 °C enable formation of mixtures between crystallographic phases of corundum-and bixbyite-type V 2 O 3 polymorphs. Depending on temperature and sputtering power, morphology and stoichiometry can be tuned to generate four distinct type of electrical transport characteristics. Most promising electrical properties of corundum V 2 O 3 with a resistance ratio of up to four orders of magnitude (during the low temperature insulator-to-metal transition) have been obtained for a moderate sputtering power of 50 W (on a 1" target) at a deposition temperature of 600 °C. Reactive sputtering thus enables direct control of structural and electrical parameters for polycrystalline V 2 O 3 thin film phases on a conducting substrate.

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“…Crystalline VO 2 ( c ‐VO 2 ) as TS element shows significant OFF‐current, which defeats its primary purpose as a selector. For this reason, a few recent studies demonstrated TS based on amorphous vanadium oxide ( a ‐VO x ). However, due to the amorphous nature of the film, devices based on same stoichiometry of vanadium oxide show multifunctional memory behavior, which is not desirable for the practical application.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13] Apolar TS property in the above papers is desirable as a selector element in crossbar arrays to reduce the sneak-path current (which disrupts stored data). For this reason, a few recent studies [10,[14][15][16] demonstrated TS based on amorphous vanadium oxide (a-VO x ). For this reason, a few recent studies [10,[14][15][16] demonstrated TS based on amorphous vanadium oxide (a-VO x ).…”

mentioning

confidence: 99%

In Situ Nanostructural Analysis of Volatile Threshold Switching and Non‐Volatile Bipolar Resistive Switching in Mixed‐Phased a‐VO_x Asymmetric Crossbars

Nirantar

Mayes

Rahman

et al. 2019

Adv Elect Materials

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structure due to its ability to be designed in high capacity 3D crossbar arrays. [1] The major disadvantage of 3D crossbars currently is the high-leakage or sneak-path current. [2] Complex class of vanadium oxide spans a broad range of 20 phases. [3] Depending on the stoichiometry, crystal structure, and device structure it has demonstrated bipolar resistive switching (BRS) [4][5][6][7][8][9][10] as well as apolar threshold switching (TS). [11][12][13] Apolar TS property in the above papers is desirable as a selector element in crossbar arrays to reduce the sneak-path current (which disrupts stored data). Crystalline VO 2 (c-VO 2 ) as TS element shows significant OFF-current, [12,13] which defeats its primary purpose as a selector. For this reason, a few recent studies [10,[14][15][16] demonstrated TS based on amorphous vanadium oxide (a-VO x ). However, due to the amorphous nature of the film, devices based on same stoichiometry of vanadium oxide show multifunctional memory behavior, [17] which is not desirable for the practical application. This variability highlights that nanostructural investigations are needed to understand the origins of different memory behaviors, in particular the reasons for observing volatile and apolar TS in a-VO x films for its practical utilization as a selector element. Further, in-depth electrical characterization is required to ascertain the electrical conditions for the occurrence of volatile or non-volatile switching in the single device.Here, we present asymmetric cross-point device (Pt/Ti/a-VO x /Pt) with ≈100 nm a-VO x film as a functional switching layer which shows multifunctional behavior in a single device. We further introduce a fabrication procedure (Section S1, Supporting Information) to incorporate a-VO x in crossbar architecture, which has been found to dissolve in water. We choose amorphous films because crystalline films are porous due to grain boundaries and pin-holes, [11] which is unsuitable for stacked architectures. Through X-ray photoelectron spectroscopy (XPS) we analyze the stoichiometry of as-deposited film which revealed the mixed-phased oxidation, including V 3+ , V 4+ , and V 5+ (corresponding to V 2 O 3 , VO 2 , and V 2 O 5 , respectively).

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Threshold Switching in Amorphous Cr-Doped Vanadium Oxide for New Crossbar Selector

Cited by 12 publications

References 10 publications

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO _x

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO _x

Competition between V2O3 phases deposited by one-step reactive sputtering process on polycrystalline conducting electrode

In Situ Nanostructural Analysis of Volatile Threshold Switching and Non‐Volatile Bipolar Resistive Switching in Mixed‐Phased a‐VO_x Asymmetric Crossbars

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Threshold Switching in Amorphous Cr-Doped Vanadium Oxide for New Crossbar Selector

Cited by 12 publications

References 10 publications

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO x

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO x

Competition between V2O3 phases deposited by one-step reactive sputtering process on polycrystalline conducting electrode

In Situ Nanostructural Analysis of Volatile Threshold Switching and Non‐Volatile Bipolar Resistive Switching in Mixed‐Phased a‐VOx Asymmetric Crossbars

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Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO _x

Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbO _x

In Situ Nanostructural Analysis of Volatile Threshold Switching and Non‐Volatile Bipolar Resistive Switching in Mixed‐Phased a‐VO_x Asymmetric Crossbars