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Journal ArticleDOI: 10.1063/1.4954166

Probing electron density across Ar+ irradiation-induced self-organized TiO2−x nanochannels for memory application

15 Jun 2016-Applied Physics Letters (AIP Publishing)-Vol. 108, Iss: 24, pp 244104
Abstract: The variation of electron density in TiO2−x nanochannels, exhibiting resistive switching phenomenon, produced by Ar+ ion-irradiation at the threshold fluence of 5 × 1016 ions/cm2 is demonstrated by X-ray reflectivity (XRR). The transmission electron microscopy reveals the formation of nanochannels, while the energy dispersive X-ray spectroscopy confirms Ti enrichment near the surface due to ion-irradiation, in consistent with the increase in electron density by XRR measurements. Such a variation in Ti concentration indicates the evolution of oxygen vacancies (OVs) along the TiO2−x nanochannels, and thus paves the way to explain the operation and performance of the Pt/TiO2−x/Pt-based memory devices via OV migration.

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Topics: Electron density (53%), X-ray reflectivity (53%)
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Open accessJournal ArticleDOI: 10.1007/S40820-016-0116-2
01 Apr 2017-Nano-micro Letters
Abstract: The resistive switching characteristics of TiO2 nanowire networks directly grown on Ti foil by a single-step hydrothermal technique are discussed in this paper. The Ti foil serves as the supply of Ti atoms for growth of the TiO2 nanowires, making the preparation straightforward. It also acts as a bottom electrode for the device. A top Al electrode was fabricated by e-beam evaporation process. The Al/TiO2 nanowire networks/Ti device fabricated in this way displayed a highly repeatable and electroforming-free bipolar resistive behavior with retention for more than 104 s and an OFF/ON ratio of approximately 70. The switching mechanism of this Al/TiO2 nanowire networks/Ti device is suggested to arise from the migration of oxygen vacancies under applied electric field. This provides a facile way to obtain metal oxide nanowire-based ReRAM device in the future.

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Topics: Nanowire (55%), Resistive random-access memory (53%), Resistive touchscreen (51%) ...read more

45 Citations


Journal ArticleDOI: 10.1088/1361-6463/AAA559
Abstract: The room temperature resistive switching behavior in 50 keV O+-ion irradiated TiO2−x layers at an ion fluence of 5 × 1016 ions cm−2 is reported. A clear transformation from columnar to layered polycrystalline films is revealed by transmission electron microscopy with increasing ion fluence, while the complementary electron energy loss spectroscopy suggests an evolution of oxygen vacancy (OV) in TiO2−x matrix. This is further verified by determining electron density with the help of x-ray reflectivity. Both local and device current–voltage measurements illustrate that the ion-beam induced OVs play a key role in bistable resistive switching mechanism.

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Topics: Electron energy loss spectroscopy (54%), Electron density (52%), Ion (52%) ...read more

12 Citations


Journal ArticleDOI: 10.1039/D0NR08214G
Abubakkar Siddik1, Prabir Kumar Haldar1, Tufan Paul2, Ujjal Das3  +3 moreInstitutions (5)
20 May 2021-Nanoscale
Abstract: Recently, several types of lead halide perovskites have been actively researched for resistive switching (RS) memory or artificial synaptic devices due to their current–voltage hysteresis along with the feasibility of fabrication, low-temperature processability and superior charge mobility. However, the toxicity and environmental pollution potential of lead halide perovskites severely restrict their large-scale commercial prospects. In the present work, the environmentally friendly and uniform CsSnCl3 perovskite films are introduced to act as an active layer in the flexible memristors. Ag/CsSnCl3/ITO devices demonstrate bipolar RS with excellent electrical properties such as forming free characteristics, good uniformity, low operating voltages, a high ON/OFF ratio (102) and a long retention time (>104 s). The RS mechanism has been well explained in the outline of electric field-induced formation and rupture of Ag filaments in the CsSnCl3 layer. The metallic nature of the conducting filament has been further confirmed by temperature-dependent variation of low and high resistance states. Additionally, various pulse measurements have been carried out to mimic some of the basic synaptic functions including postsynaptic current, paired-pulse facilitation, long-term potentiation and long-term depression under normal as well as bending conditions. Our work provides the opportunity for exploring artificial synapses based on lead-free halide perovskites for the development of next-generation flexible electronics.

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7 Citations


Journal ArticleDOI: 10.1016/J.APSUSC.2019.04.114
Xinqiang Pan1, Xinqiang Pan2, Yao Shuai2, Wu Chuangui2  +14 moreInstitutions (4)
Abstract: Recently, memristors have attracted considerable attention because of their potential applications in artificial neural networks which will promote the future development of artificial intelligence. In this work, the analogue memristive and related synaptic behavior of memristors based on single crystalline LiNbO3 thin films have been studied. Low energy Ar+ ions irradiation was applied to locally dope the LiNbO3 thin films by controllably introducing oxygen vacancies acting as donors. The resistive switching performance and synaptic plasticity can be tuned by changing the size or the number of the irradiated regions below the top electrode. Linear regression, an important fundamental function belonging to the machine learning in artificial intelligence, was emulated using memristors with different synaptic plasticity. It has been shown that the local doping method significantly influences the linear regression process.

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Topics: Neuromorphic engineering (56%)

6 Citations


Journal ArticleDOI: 10.1557/JMR.2018.411
Yuxin Li1, Rong Fu1, Xiangdong Wang1, Xiaoling Guo2Institutions (2)
Abstract: Black nano-TiO2 samples with core–shell nanostructure were successfully prepared by sol–gel method combined with Mg reduction using butyl titanate as titanium source and calcining at 500°C in air atmosphere and at 400–600°C in nitrogen atmosphere. The prepared black TiO2 samples were characterized by X-ray diffraction, high resolution transmission electron microscopy, Raman spectra, photoluminescence emission spectra, N2 adsorption–desorption, and ultraviolet–visible spectroscopy. The results show that the black TiO2 exhibits a crystalline core–disordered shell structure composed of disordered surface and oxygen vacancies, and the thickness of the disordered layer is about 2–3 nm. The optical absorption properties of black nano-TiO2 samples have been remarkably enhanced in visible light region. Compared with the white TiO2, the reduced black TiO2 samples exhibit enhanced photocatalytic hydrogen production under the full solar wavelength range of light, and the sample prepared with the Mg and TiO2 ratio of 9:1 calcined at 500 °C has the maximum hydrogen production rate.

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2 Citations


References
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Journal ArticleDOI: 10.1016/J.NIMB.2010.02.091
Abstract: SRIM is a software package concerning the S topping and R ange of I ons in M atter. Since its introduction in 1985, major upgrades are made about every six years. Currently, more than 700 scientific citations are made to SRIM every year. For SRIM-2010 , the following major improvements have been made: (1) About 2800 new experimental stopping powers were added to the database, increasing it to over 28,000 stopping values. (2) Improved corrections were made for the stopping of ions in compounds. (3) New heavy ion stopping calculations have led to significant improvements on SRIM stopping accuracy. (4) A self-contained SRIM module has been included to allow SRIM stopping and range values to be controlled and read by other software applications. (5) Individual interatomic potentials have been included for all ion/atom collisions, and these potentials are now included in the SRIM package. A full catalog of stopping power plots can be downloaded at www.SRIM.org . Over 500 plots show the accuracy of the stopping and ranges produced by SRIM along with 27,000 experimental data points. References to the citations which reported the experimental data are included.

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5,498 Citations


Journal ArticleDOI: 10.1103/PHYSREV.95.359
Lyman G. Parratt1Institutions (1)
15 Jul 1954-Physical Review
Abstract: Analysis of the shape of the curve of reflected x-ray intensity vs glancing angle in the region of total reflection provides a new method of studying certain structural properties of the mirror surface about 10 to several hundred angstroms deep. Dispersion theory, extended to treat any (small) number of stratified homogeneous media, is used as a basis of interpretation.Curves for evaporated copper on glass at room temperature are studied as an example. These curves may be explained by assuming that the copper (exposed to atmospheric air at room temperature) has completely oxidized about 150A deep. If oxidation is less deep, there probably exists some general reduction of density (e.g., porosity) and an electron density minimum just below an internal oxide seal. This seal, about 25A below the nominal surface plane, arrests further oxidation of more deeply-lying loose-packed copper crystallites.All measurements to date have been carried out under laboratory atmospheric conditions which do not allow satisfactory separation or control of the physical and chemical variables involved in the surface peculiarities. The method, under more controlled conditions of preparation and treatment of the surface, promises to be useful.

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Topics: Total internal reflection (53%), Copper (50%), Grazing incidence diffraction (50%) ...read more

4,220 Citations


Journal ArticleDOI: 10.1109/JPROC.2012.2190369
Hon-Sum Philip Wong1, Heng-Yuan Lee, Shimeng Yu1, Yu-Sheng Chen  +5 moreInstitutions (1)
02 May 2012-
Abstract: In this paper, recent progress of binary metal-oxide resistive switching random access memory (RRAM) is reviewed. The physical mechanism, material properties, and electrical characteristics of a variety of binary metal-oxide RRAM are discussed, with a focus on the use of RRAM for nonvolatile memory application. A review of recent development of large-scale RRAM arrays is given. Issues such as uniformity, endurance, retention, multibit operation, and scaling trends are discussed.

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1,891 Citations


Open accessJournal ArticleDOI: 10.1103/PHYSREVLETT.81.3014
Abstract: The long-standing problem of growing a commensurate crystalline oxide interface with silicon has been solved. Alkaline earth and perovskite oxides can be grown in perfect registry on the (001) face of silicon, totally avoiding the amorphous silica phase that ordinarily forms when silicon is exposed to an oxygen containing environment. The physics of the heteroepitaxy lies in establishing a sequenced transition that uniquely addresses the thermodynamics of a layer-by-layer energy minimization at the interface. A metal-oxide-semiconductor capacitor using SrTiO{sub 3} as an alternative to SiOthinsp{sub 2} yields the extraordinary result of t{sub eq}{lt}10 {Angstrom} . {copyright} {ital 1998} {ital The American Physical Society}

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Topics: Silicon (53%)

916 Citations


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