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Reconfigurable Filamentary Conduction in Thermally Stable Zeolitic Imidazolate Framework (ZIF-8) Resistive Switching Devices
Authors:
Divya Kaushik,
Nitin Kumar,
Harshit Sharma,
Pukhraj Prajapat,
Mehamalini V.,
G. Sambandamurthy,
Ritu Srivastava
Abstract:
The rapid growth of digital technology has driven the need for efficient storage solutions, positioning memristors as promising candidates for next-generation non-volatile memory (NVM) due to their superior electrical properties. Organic and inorganic materials each offer distinct advantages for resistive switching (RS) performance, while hybrid materials like metal-organic frameworks (MOFs) combi…
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The rapid growth of digital technology has driven the need for efficient storage solutions, positioning memristors as promising candidates for next-generation non-volatile memory (NVM) due to their superior electrical properties. Organic and inorganic materials each offer distinct advantages for resistive switching (RS) performance, while hybrid materials like metal-organic frameworks (MOFs) combine the strengths of both. In this study, we present a resistive random-access memory (ReRAM) device utilizing zeolitic imidazolate framework (ZIF-8), a MOF material, as the resistive switching layer. The ZIF-8 film was synthesized via a simple solution process method at room temperature and subsequently characterized. The Al/ZIF-8/ITO device demonstrates bipolar resistive switching behaviour with an on/off resistance ratio of 100, stable retention up to 10000 seconds, and consistent performance across 60 cycles while exhibiting robust thermal stability from -20 C to 100 C. Low-frequency noise and impedance spectroscopy measurements suggest a filamentary switching mechanism. Additionally, the memory state can be tuned by adjusting the reset voltage, pointing to potential as multi-level memory. Potentiation and depression experiments further highlight the devices promise for neuromorphic applications. With high stability, tunability, and strong performance, the ZIF-8 based ReRAM shows great promise for advanced NVM and neuromorphic computing applications.
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Submitted 3 January, 2025;
originally announced January 2025.
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Ion-beam sputtering of NiO hole transporting layers for p-i-n halide perovskite solar cells
Authors:
P. Gostishchev,
L. O. Luchnikov,
O. Bronnikov,
V. Kurichenko,
D. S. Muratov,
A. A. Aleksandrov,
A. R. Tameev,
M. P. Tyukhova,
S. Le Badurin. I. V.,
Ryabtseva M. V.,
D. Saranin,
A. Di Carlo
Abstract:
Ion-beam sputtering offers significant benefits in terms of deposition uniformity and pinhole-free thin-films without limiting the scalability of the process. In this work, the reactive ion-beam sputtering of nickel oxide has been developed for the hole transporting layer of a p-i-n perovskite solar cells (PCSs). The process is carried out by oxidation of the scattered Ni particles with additional…
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Ion-beam sputtering offers significant benefits in terms of deposition uniformity and pinhole-free thin-films without limiting the scalability of the process. In this work, the reactive ion-beam sputtering of nickel oxide has been developed for the hole transporting layer of a p-i-n perovskite solar cells (PCSs). The process is carried out by oxidation of the scattered Ni particles with additional post-treatment annealing regimes. Using deposition rate of 1.2 nm/min allowed growth of very uniform NiO coating with the roughness below 0.5 nm on polished Si wafer (15x15 cm2). We performed a complex investigation of structural, optical, surface and electrical properties of the NiO thin-films. The post-treatment annealing (150-300C) was considered as an essential process for improvement of the optical transparency, decrease of defects concentration and gain of the charge carrier mobility. As result, the annealed ion-beam sputtered NiO films delivered a power conversion efficiency (PCE) up to 20.14%, while device without post-treatment reached the value of 11.84%. The improvement of the output performance originated from an increase of the short-circuit current density (Jsc), open circuit voltage (Voc), shunt and contact properties in the devices. We also demonstrate that the ion-beam sputtering of NiO can be successfully implemented for the fabrication of large area modules (54.5 cm2) and PSCs on a flexible plastic substrate (125 microns).
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Submitted 29 June, 2023;
originally announced June 2023.
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Photoinduced modulation of refractive index in Langmuir-Blodgett films of Azo-based H-shaped liquid crystal molecules
Authors:
Ashutosh Joshi,
Akash Gayakwad,
Manjuladevi V.,
Mahesh C. Varia,
S. Kumar,
R. K. Gupta
Abstract:
The development of optically active area consisting of organic molecules are essential for the devices like optical switches and waveguides, as it can be easily maneuvered by the application of suitable electromagnetic (EM) waves. In this article, we report the development of a photoactive surface by the deposition of a single layer of Langmuir-Blodgett (LB) film of a novel H-shaped liquid crystal…
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The development of optically active area consisting of organic molecules are essential for the devices like optical switches and waveguides, as it can be easily maneuvered by the application of suitable electromagnetic (EM) waves. In this article, we report the development of a photoactive surface by the deposition of a single layer of Langmuir-Blodgett (LB) film of a novel H-shaped liquid crystal (HLC) molecule. The synthesized HLC molecules possess azo-groups and nitro-groups. The azo-group can be isomerized (trans-cis transformation) by irradiating them with ultraviolet (UV) light. The nitro-group can provide sufficient amphiphilicity to the HLC molecules to form a stable Langmuir monolayer at air-water interface. The Langmuir monolayer of the HLC molecules exhibited gas and liquid-like phases. A single layer of LB film of HLC molecules was deposited on a gold chip of a home-built surface plasmon resonance (SPR) instrument. The azo-groups of the molecules in LB film was excited by UV irradiation leading to a change in morphology due to trans-cis transformation. Such a change in morphology can lead to a miniscule change in refractive index (RI) of the LB film. SPR is a label free and highly sensitive optical phenomenon for the measurement of such changes in RI. In our studies, we found systematic changes in the resonance angle of the LB film of HLC molecules as a function of intensity of the UV irradiation. We measured switch-on and switch-off intensity which may suggest that the LB film of HLC molecules can find applications in optical switches or waveguides.
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Submitted 13 August, 2022;
originally announced August 2022.
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Investigation of the effect of the grain sizes on the dynamic strength of the fine-grained alumina ceramics obtained by Spark Plasma Sintering
Authors:
Melekhin N. V.,
Boldin M. S.,
Bragov A. M.,
Filippov A. R.,
Popov A. A.,
Shotin S. V.,
Nokhrin A. V.,
Chuvil'deev V. N.,
Murashov A. A.,
Tabachkova N. Yu.
Abstract:
The results of dynamic strength tests of the alumina ceramics with various grain sizes are presented. The ceramics were obtained by Spark Plasma Sintering (SPS) of industrial submicron and fine Al2O3 powders. The heating up was performed with the rate of 10 oC/min; the grain sizes in the ceramics was controlled by varying the SPS temperature and the heating rate as well as by varying the initial s…
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The results of dynamic strength tests of the alumina ceramics with various grain sizes are presented. The ceramics were obtained by Spark Plasma Sintering (SPS) of industrial submicron and fine Al2O3 powders. The heating up was performed with the rate of 10 oC/min; the grain sizes in the ceramics was controlled by varying the SPS temperature and the heating rate as well as by varying the initial sizes of the Al2O3 particles in the powders. The ceramics had a high density (over 98%) and a uniform fine-grained microstructure (the mean grain sizes varied from 0.8 to 13.4 mkm). The dynamic compressing tests were carried out by modified Kolsky method with using split Hopkinson pressure bar. The tests were performed at room temperature using a 20-mm PG-20 gas gun with the strain rate of ~10^3 s-1. The dependence of the dynamic ultimate strength of alumina on the grain size was found for the first time to have a non-monotonous character (with a maximum). The maximum value of the dynamic ultimate compression strength (SY = 1060 MPa) was provided at the mean grain size of ~2.9-3 mkm. The reduction of SY for alumina in the range of submicron grain sizes was shown to originate from the reduction of the relative density of the ceramics sintered at lower SPS temperatures.
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Submitted 21 April, 2022;
originally announced April 2022.
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Anomalous phase shift of Shubnikov - de Haas oscillations in HgTe quantum well with inverted energy spectrum
Authors:
Neverov V. N.,
Klepikova A. S.,
Bogolubskii A. S.,
Gudina S. V.,
Turutkin K. V.,
Shelushinina N. G. 1,
Yakunin M. V.,
N. N. Mikhailov,
S. A. Dvoretsky
Abstract:
The results of the longitudinal and Hall magnetoresistivity measurements in the Shubnikov - de Haas oscillation regime for the HgCdTe/HgTe/HgCdTe heterostructures with a wide (20.3 nm) HgTe quantum well are presented. An anomalous phase shift of magneto-oscillations is detected: in the region of spin-unsplit peaks the longitudinal resistivity maxima are located at even filling factor numbers in co…
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The results of the longitudinal and Hall magnetoresistivity measurements in the Shubnikov - de Haas oscillation regime for the HgCdTe/HgTe/HgCdTe heterostructures with a wide (20.3 nm) HgTe quantum well are presented. An anomalous phase shift of magneto-oscillations is detected: in the region of spin-unsplit peaks the longitudinal resistivity maxima are located at even filling factor numbers in contradiction with a conventional situation in 2D systems. It is shown that the observed features are associated with the inverted nature of the spectrum in the investigated quantum well with the electron-type conduction along the size-quantized subband H1 of HgTe band Γ8, for which the spin splitting is comparable to (and even greater than) the orbital one. The results obtained are compared with the phase shift effects of both magneto-oscillations and the plateau of the quantum Hall effect in monolayer graphene.
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Submitted 6 February, 2020;
originally announced February 2020.
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GdFe$_2$ Laves phase intermetallic system under pressure: an ab-initio study
Authors:
Kokorina E. E.,
Medvedev M. V.,
Nekrasov I. A
Abstract:
Here we perform $ab-initio$ study of Curie temperature $T_C$ under hydrostatic pressure for intermetallic compound GdFe$_2$. To calculate $T_C$ for GdFe$_2$ we applied mean-field solution of the Heisenberg model for several magnetic sublattices with DFT/LDA calculated values of necessary exchange interaction integrals and local magnetic moments. To compare with available experimental data pressure…
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Here we perform $ab-initio$ study of Curie temperature $T_C$ under hydrostatic pressure for intermetallic compound GdFe$_2$. To calculate $T_C$ for GdFe$_2$ we applied mean-field solution of the Heisenberg model for several magnetic sublattices with DFT/LDA calculated values of necessary exchange interaction integrals and local magnetic moments. To compare with available experimental data pressure values were taken from zero up to about 70 Kbar. It corresponds to 2\% compression of the volume of the unit cell. In agreement with experimental data $T_C$ grows under pressure. It was shown that Fe ions magnetic sublattice alone provides only about 75\% of the experimental Curie temperature $T_C^{exp}$. Gd sublattice is found to give very weak contribution to the $T_C^{exp}$. Here we show that the missing 25 \% of $T_C^{exp}$ comes from Fe-Gd exchange pairs.
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Submitted 22 July, 2019;
originally announced July 2019.
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Kondo effect in side coupled double quantum-dot molecule
Authors:
Gustavo A. Lara,
Pedro A. Orellana,
J. Yanez,
Enrique V. Anda
Abstract:
Electron tunneling through a double quantum dot molecule side attached to a quantum wire, in the Kondo regime, is studied. The mean-field finite-U slave-boson formalism is used to obtain the solution of the problem. We found conductance cancelations when the molecular energies of the side attached double quantum-dot cross the Fermi energy. We investigate the many body molecular Kondo states as a…
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Electron tunneling through a double quantum dot molecule side attached to a quantum wire, in the Kondo regime, is studied. The mean-field finite-U slave-boson formalism is used to obtain the solution of the problem. We found conductance cancelations when the molecular energies of the side attached double quantum-dot cross the Fermi energy. We investigate the many body molecular Kondo states as a function of the parameters of the system.
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Submitted 25 November, 2004;
originally announced November 2004.
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Theory of the phase transition from a disordered cubic crystal to a glass
Authors:
J. M. Yanez,
M. I. Molina,
D. C. Mattis
Abstract:
We calculate thermodynamic properties of a disordered model insulator, starting from the ideal simple-cubic lattice ($g = 0$) and increasing the disorder parameter $g$ to $\gg 1/2$. As in the earlier Einstein- and Debye- approximations, the ground state energy is discontinuous at $g_{c} = 1/2$. For $g<g_{c}$ the low-T heat-capacity $C \sim T^{3}$ whereas for $g>g_{c}$, $C \sim T$. The van Hove s…
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We calculate thermodynamic properties of a disordered model insulator, starting from the ideal simple-cubic lattice ($g = 0$) and increasing the disorder parameter $g$ to $\gg 1/2$. As in the earlier Einstein- and Debye- approximations, the ground state energy is discontinuous at $g_{c} = 1/2$. For $g<g_{c}$ the low-T heat-capacity $C \sim T^{3}$ whereas for $g>g_{c}$, $C \sim T$. The van Hove singularities disappear at {\em any} finite magnitude $g$ of the disorder. For $g>1/2$ we discover novel {\em fixed points} in the self-energy and spectral density of this model glass.
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Submitted 20 April, 2001;
originally announced April 2001.
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From Disordered Crystal to Glass: Exact Theory
Authors:
J. M. Yanez,
M. I. Molina,
D. C. Mattis
Abstract:
We calculate thermodynamic properties of a disordered model insulator, starting from the ideal simple-cubic lattice ($g = 0$) and increasing the disorder parameter $g$ to $\gg 1/2$. As in earlier Einstein- and Debye- approximations, there is a phase transition at $g_{c} = 1/2$. For $g<g_{c}$ the low-T heat-capacity $C \sim T^{3}$ whereas for $g>g_{c}$, $C \sim T$. The van Hove singularities disa…
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We calculate thermodynamic properties of a disordered model insulator, starting from the ideal simple-cubic lattice ($g = 0$) and increasing the disorder parameter $g$ to $\gg 1/2$. As in earlier Einstein- and Debye- approximations, there is a phase transition at $g_{c} = 1/2$. For $g<g_{c}$ the low-T heat-capacity $C \sim T^{3}$ whereas for $g>g_{c}$, $C \sim T$. The van Hove singularities disappear at {\em any finite $g$}. For $g>1/2$ we discover novel {\em fixed points} in the self-energy and spectral density of this model glass.
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Submitted 16 February, 2001;
originally announced February 2001.