A5082138846- Graphene research and applications
- 2D Materials and Applications
- Semiconductor materials and devices
- Carbon Nanotubes in Composites
- Advanced Memory and Neural Computing
- Semiconductor materials and interfaces
- Perovskite Materials and Applications
- Copper Interconnects and Reliability
- Quantum and electron transport phenomena
- Advancements in Semiconductor Devices and Circuit Design
- Topological Materials and Phenomena
- Advancements in Battery Materials
- Neuroscience and Neural Engineering
- Fuel Cells and Related Materials
- Molecular Junctions and Nanostructures
- Advanced biosensing and bioanalysis techniques
- Diamond and Carbon-based Materials Research
- Graphene and Nanomaterials Applications
- Nanowire Synthesis and Applications
- Plasmonic and Surface Plasmon Research
- Boron and Carbon Nanomaterials Research
- Silicon and Solar Cell Technologies
- Heat Transfer and Boiling Studies
- Refrigeration and Air Conditioning Technologies
- Electronic Packaging and Soldering Technologies
Indian Institute of Technology Madras
2018-2025
University of Manchester
1982-2021
Henry Royce Institute
2016-2021
Indian Institute of Technology Bombay
2010-2014
Los Alamos National Laboratory
2006
Louisiana State University
2003
Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays crucial role phenomena, such as Klein tunneling, but it difficult to visualize directly. Here, we report direct observation manipulation chirality pseudospin polarization tunneling between two almost perfectly aligned crystals. We use strong in-plane magnetic field tool resolve contributions chiral electronic states that have phase difference components their...
We observe a series of sharp resonant features in the differential conductance graphene-hexagonal boron nitride-graphene tunnel transistors over wide range bias voltages between 10 and 200 mV. attribute them to electron tunneling assisted by emission phonons well-defined energy. The at which they occur are insensitive applied gate voltage hence independent carrier densities graphene electrodes, so plasmonic effects can be ruled out. phonon energies corresponding resonances compared with...
Abstract Semiconducting ferromagnet-nonmagnet interfaces in van der Waals heterostructures present a unique opportunity to investigate magnetic proximity interactions dependent upon multitude of phenomena including valley and layer pseudospins, moiré periodicity, or exceptionally strong Coulomb binding. Here, we report charge-state dependency the effects between MoSe 2 CrBr 3 photoluminescence, whereby polarization trion state conforms closely local magnetization, while neutral exciton...
Despite a rich choice of two-dimensional materials, which exists these days, heterostructures, both vertical (van der Waals) and in-plane, offer an unprecedented control over the properties functionalities resulted structures. Thus, planar heterostructures allow p-n junctions between different semiconductors graphene nanoribbons with well-defined edges; in observation superconductivity purely carbon-based systems realisation tunnelling transistors. Here we demonstrate simultaneous use...
Abstract ReS 2 crystallizes in low crystal symmetry distorted triclinic (1T’) structure, and has anisotropic optical properties. Recently, two different stacking orders named as AA AB phases, have been identified with distinct characteristics, such order dependent Raman shift, carrier dynamics, second harmonic generation (SHG). However, the structure combined sequences complicate understanding of responses this material thus instigating debate on interlayer coupling, number excitonic...
Work function (WF) tuning of the contact electrodes is a key requirement in several device technologies, including organic photovoltaics (OPVs), light-emitting diodes (OLEDs), and complementary metal oxide semiconductor (CMOS) transistors. Here, we demonstrate that WF gate electrode an MOS structure can be modulated from 4.35 eV (n-type metal) to 5.28 (p-type by sandwiching different thicknesses reduced graphene (rGO) layers between top metals dielectric SiO2. The shows strong dependence on...
Hexagonal boron nitride (hBN) is a large band gap layered crystal, frequently incorporated in van der Waals (vdW) heterostructures as an insulating or tunnel barrier. Localised states with energies within its can emit visible light, relevant to applications nanophotonics and quantum information processing. However, they also give rise conducting channels, which induce electrical breakdown when voltage applied. Here we use gated transistors study resonant electron tunnelling through the...
Abstract Memristors‐based integrated circuits for emerging bio‐inspired computing paradigms require an approach utilizing both volatile and nonvolatile memristive devices. Here, innovative architecture comprising of 1D CVD‐grown core–shell heterostructures (CSHSs) MoO 2 ‐MoS is employed as memristors manifesting switching (with high selectivity 10 7 steep slope 0.6 mV decade −1 ) phenomena I on / off ≈10 3 speed 60 ns). In these CSHSs, the metallic core with current carrying capacity...
Crystallographic alignment between two-dimensional crystals in van der Waals heterostructures brought a number of profound physical phenomena, including observation Hofstadter butterfly and topological currents, promising novel applications, such as resonant tunnelling transistors. Here, by probing the electronic density states graphene using graphene-hexagonal boron nitride-graphene transistors, we demonstrate structural transition bilayer from incommensurate twisted stacking state into...
Charge storage capability of multilayer graphene (MLG) in floating gate flash memory structure is demonstrated. MLG sheets are considered for this purpose because the higher work function and density states compared to single layer (SLG) lower conductivity along c-axis. A window 6.8V 1 second programming obtained at ±18V program/erase voltage. Number electrons stored after 18V voltage calculated as 9.1 x 1012 cm-2 which than SLG, suggesting suitability multi level data devices.
Graphene with varying number of layers is explored as metal gate electrode in oxide semiconductor structure by inserting it between the dielectric (SiO2) and contact (TiN) results are compared TiN electrode. We demonstrate an effective work function tuning upto 0.5 eV graphene layers. Inclusion even 1-3 significantly improved reliability measured breakdown characteristics, charge to breakdown, interface state density. These improvements attributed impermeability for hence reduced metallic...
In this paper, we report on the surface passivation of crystalline silicon (c-Si) by pulsed-dc (p-dc) reactive-sputtered aluminum oxide (AlO <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> ) films. For activation passivation, films were subjected to post deposition annealing (PDA) in different ambients namely N <sub xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , + O and forming gas (FG) temperature range 420-520°C. The was quantified...
In this paper, we present a detailed study of temperature-based ion implantation phosphorus dopants in Ge for varying dose and anneal conditions through fabricated n+/p junctions n-type MOSFETs (nMOSFETs). comparison with room temperature (RT) (25 °C) hot (400 implantation, cryogenic (-100 2.2e15 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> followed by rapid thermal annealing leads to 1) lower junction leakage higher activation...
Synthesizing a material with the desired polymorphic phase in chemical vapor deposition (CVD) process requires delicate balance among various thermodynamic variables. Here, we present methodology to synthesize rhombohedral (3R)-phase MoS2 well-defined sword-like geometry having lengths up 120 μm, uniform width of 2-3 μm and thickness 3-7 nm by controlling carrier gas flow dynamics from continuous mode pulsed during CVD growth process. Characteristic signatures such as high degree circular...
The ultimate limit of control light at the nanoscale is atomic scale. By stacking multiple layers graphene on hexagonal boron nitride (h-BN), heterostructures with unique nanophotonic properties can be constructed, where distance between plasmonic materials controlled atom-scale precision. Here we show how an atomically thick tunable quantum tunnelling device used as a building block for plasmonics. consists two separated by 1 nm (three monolayers) h-BN, and bias voltage generates electron...
We prepare twist-controlled resonant tunneling transistors consisting of monolayer and Bernal bilayer graphene electrodes separated by a thin layer hexagonal boron nitride. The conditions are achieved closely aligning the crystallographic orientation electrodes, which leads to momentum conservation for electrons at certain bias voltages. Under such conditions, negative differential conductance can be achieved. Application in-plane magnetic field acquiring additional during process, allows...
Two-dimensional layered transition metal dichalcogenides (TMDCs) offer the ideal platform to optically initialize qubits utilizing superposition of valley polarized photons. However, in commonly available 2H phase TMDCs, thickness sensitive crystal inversion symmetry demands precise control over number layers, which makes study physics challenging. On other hand, 3R-polymorphic TMDCs are non-centrosymmetric irrespective layers and therefore retain degree freedom for all thicknesses. Here,...
The discovery of graphene in the early 2000s led to rapid development an emerging class material system, now widely known as two-dimensional (2D) materials. atomic-scale thickness 2D materials leads rich transport physics beneficial for many electronic/optoelectronic devices. transition-metal dichalcogenides (2D-TMDCs) have been investigated logic applications over past decade. However, out-of-plane ultrathin 2D-TMDCs and resulting memristive devices remain relatively less explored....
Memristive devices based on layered materials have the potential to enable low power electronics with ultra-fast operations toward development of next generation memory and computing technologies. Memristor performance switching behavior crucially depend matrix type electrodes used. In this work, we investigate effect different in 1D MoO2–MoS2 core shell nanowire memristors by highlighting their role achieving distinct behavior. Analog digital resistive are realized carbon passive...
The work function (WF) of a material governs the back and forth movement charge carriers across hetero-interface two materials. Therefore, for optimum device performance, precise knowledge WF is prerequisite while employing any new in electronic devices. In this work, using metal oxide semiconductor capacitors, we experimentally determine layered van der Waals topological semimetals (TSMs) 1T′-MoTe2, 1T-PtSe2, Td-WTe2 as 4.87, 5.05, 4.82 eV, respectively. obtained results are corroborated...
We report the healing of electrically broken multiwalled carbon nanotubes (MWNTs) using very low energy electrons (3−10 keV) in scanning electron microscopy (SEM). Current-induced breakdown caused by Joule heating has been achieved applying suitably high voltages. The tubes were examined and exposed to 3−10 keV situ SEM with careful maneuvering beam at site, which results mechanical joining tube. Electrical recovery same tube confirmed performing current−voltage measurements after joining....
The effect of position top metal contact on the electrical transport through individual multiwalled carbon nanotubes (MWNTs) has been investigated using gas injection system in situ scanning electron microscope to deposit platinum contacts at different desired sites side contacted MWNTs bridging structure. Current-voltage measurements reveal a significant improvement properties tubes after is made. This found be independent contact, i.e., whether made ends or any other site tube.
We nominate the nickel filled multiwalled carbon nanotubes (MWNTs) as potential candidates to cope with challenges in persistent scaling for future interconnect technology. The insights into electrical transport through provide an effective solution major performance and reliability issues such increasing resistivity of metals at reduced scales, electromigration high current densities problem diffusion corrosion faced by existing copper Furthermore, MWNTs outperform their hollow...