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A. Barman

Bio: A. Barman is an academic researcher from Shiv Nadar University. The author has contributed to research in topics: Nanorod & Transmission electron microscopy. The author has an hindex of 10, co-authored 24 publications receiving 252 citations. Previous affiliations of A. Barman include Indian Institute of Technology Delhi & Indian Institutes of Technology.

Papers
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Journal ArticleDOI
15 Apr 2020
TL;DR: In this paper, the inorganic halide perovskites are considered as favorable materials for various electronic applications because of their superior functionality and stability, and they are used for various applications.
Abstract: All-inorganic halide perovskites are considered as favorable materials for various electronic applications because of their superior functionality and stability. In this study, the inorganic rubidi...

43 citations

Journal ArticleDOI
TL;DR: The environmentally friendly and uniform CsSnCl3 perovskite films are introduced to act as an active layer in the flexible memristors for the development of next-generation flexible electronics.
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.

41 citations

Journal ArticleDOI
TL;DR: It was found that nonvolatile and stable resistance levels, especially the multiple low-resistance states of Cu/NiO y /NiO x /Pt memory devices, could be controlled by varying the compliance current.
Abstract: The application of a NiO y /NiO x bilayer in resistive switching (RS) devices with x > y was studied for its ability to achieve reliable multilevel cell (MLC) characteristics. A sharp change in resistance brought about by sweeping the voltage, along with an improved on/off ratio (>103) and endurance (104) were achieved in the bilayer structure as compared to the single NiO x layer devices. Moreover, it was found that nonvolatile and stable resistance levels, especially the multiple low-resistance states of Cu/NiO y /NiO x /Pt memory devices, could be controlled by varying the compliance current. All the multilevel resistance states of the Cu/NiO y /NiO x /Pt bilayer devices were stable for up to 500 consecutive dc switching cycles, as compared to the Cu/NiO x /Pt single layer devices. The temperature-dependent variation of the high and low resistance states of both the bilayer and single layer devices was further investigated to elucidate the charge conduction mechanism. Finally, based on a detailed analysis of the experimental results, comparisons of the possible models for RS in bilayer and single layer memory devices have also been discussed.

39 citations

Journal ArticleDOI
TL;DR: In this article, temperature-dependent photoluminescence (PL) of titanium oxide (TiO2) shows an evolution of blue emission when exposed to 50 keV Ar+ ions.
Abstract: Temperature-dependent photoluminescence (PL) of titanium oxide (TiO2) shows an evolution of blue emission when exposed to 50 keV Ar+ ions. The origin of observed PL has been examined by X-ray absorption near-edge spectroscopy (XANES) at Ti-K,L and O-K edges, revealing the reduction of ligand field splitting owing to the formation of oxygen vacancies (OVs) by destroying TiO6 octahedral symmetry. Detailed PL and XANES analyses suggest that the fluence (ions/cm2) dependent increase in OVs not only boosts the conduction electrons but also increases the density of holes in localized self-trapped exciton (STE) states near the valence band. Based on these observations, we propose a model in which doped conduction electrons are recombining radiatively with the holes in STE states for blue light emission.

37 citations

Journal ArticleDOI
TL;DR: In this article, a facile NaCl-assisted Chemical Vapor Deposition (CVD) synthesis of high-quality MoS2 on amorphous, crystalline and layered substrates is reported.

33 citations


Cited by
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TL;DR: This review highlights different strategies for effectively introducing oxygen vacancies in titanium oxide-based nanomaterials, as well as a discussion on the positions of oxygen vacancies inside the TiO2 band gap based on theoretical calculations.
Abstract: TiO2 and other titanium oxide-based nanomaterials have drawn immense attention from researchers in different scientific domains due to their fascinating multifunctional properties, relative abundance, environmental friendliness, and bio-compatibility. However, the physical and chemical properties of titanium oxide-based nanomaterials are found to be explicitly dependent on the presence of various crystal defects. Oxygen vacancies are the most common among them and have always been the subject of both theoretical and experimental research as they play a crucial role in tuning the inherent properties of titanium oxides. This review highlights different strategies for effectively introducing oxygen vacancies in titanium oxide-based nanomaterials, as well as a discussion on the positions of oxygen vacancies inside the TiO2 band gap based on theoretical calculations. Additionally, a detailed review of different experimental techniques that are extensively used for identifying oxygen vacancies in TiO2 nanostructures is also presented.

258 citations

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TL;DR: A broad review of oxide-based RRAM materials that can be adapted to neuromorphic computing and to help further ongoing research in the field is given.
Abstract: In this review, a comprehensive survey of different oxide-based resistive random-access memories (RRAMs) for neuromorphic computing is provided. We begin with the history of RRAM development, physical mechanism of conduction, fundamental of neuromorphic computing, followed by a review of a variety of RRAM oxide materials (PCMO, HfOx, TaOx, TiOx, NiOx, etc.) with a focus on their application for neuromorphic computing. Our goal is to give a broad review of oxide-based RRAM materials that can be adapted to neuromorphic computing and to help further ongoing research in the field.

171 citations

Journal Article
TL;DR: In situ Raman and ultraviolet-visible spectroscopy alongside spectroelectrochemistry and quantum chemical calculations demonstrate that the redox state of the ligands determines the switching states of the device whereas the counterions control the hysteresis, which may accelerate the technological deployment of organic resistive memories.
Abstract: Non-volatile memories will play a decisive role in the next generation of digital technology. Flash memories are currently the key player in the field, yet they fail to meet the commercial demands of scalability and endurance. Resistive memory devices, and in particular memories based on low-cost, solution-processable and chemically tunable organic materials, are promising alternatives explored by the industry. However, to date, they have been lacking the performance and mechanistic understanding required for commercial translation. Here we report a resistive memory device based on a spin-coated active layer of a transition-metal complex, which shows high reproducibility (∼350 devices), fast switching (≤30 ns), excellent endurance (∼1012 cycles), stability (>106 s) and scalability (down to ∼60 nm2). In situ Raman and ultraviolet-visible spectroscopy alongside spectroelectrochemistry and quantum chemical calculations demonstrate that the redox state of the ligands determines the switching states of the device whereas the counterions control the hysteresis. This insight may accelerate the technological deployment of organic resistive memories.

163 citations

Journal Article
TL;DR: In this paper, a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons was proposed to increase the red shift and broadening of the signal from microcrystalline silicon films.
Abstract: The red shift and the broadening of the Raman signal from microcrystalline silicon films is described in terms of a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons. The relationship between width and shift calculated from the known dispersion relation in c-Si is in good agreement with available data. An increase in the decay rate of the optical phonons predicted on the basis of the same model is confirmed experimentally.

105 citations

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TL;DR: Results show that the modification of ZnO with iron or copper oxides enhances the hydrophobic behavior of the surface, increasing the contact angle of the water drops at the non-modified ZnNO structures from 122° to 135° and 145° for Fe2O3@ZnO and CuO@znO, respectively.
Abstract: Non-modified (ZnO) and modified (Fe2O3@ZnO and CuO@ZnO) structured films are deposited via aerosol assisted chemical vapor deposition. The surface modification of ZnO with iron or copper oxides is achieved in a second aerosol assisted chemical vapor deposition step and the characterization of morphology, structure, and surface of these new structured films is discussed. X-ray photoelectron spectrometry and X-ray diffraction corroborate the formation of ZnO, Fe2O3, and CuO and the electron microscopy images show the morphological and crystalline characteristics of these structured films. Static water contact angle measurements for these structured films indicate hydrophobic behavior with the modified structures showing higher contact angles compared to the non-modified films. Overall, results show that the modification of ZnO with iron or copper oxides enhances the hydrophobic behavior of the surface, increasing the contact angle of the water drops at the non-modified ZnO structures from 122° to 135° and 145° for Fe2O3@ZnO and CuO@ZnO, respectively. This is attributed to the different surface properties of the films including the morphology and chemical composition.

84 citations