6 results on '"Arindam Ghosh"'
Search Results
2. Enhancement of thermal and mechanical properties of few layer boron nitride reinforced PET composite
- Author
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Joseph Berkmans, T. Phanindra Sai, Prasad S. Upasani, Anindita Sahoo, H N Gayathri, Arindam Ghosh, and Vivek Raje
- Subjects
Materials science ,Bioengineering ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Crystallinity ,chemistry.chemical_compound ,Differential scanning calorimetry ,law ,Polyethylene terephthalate ,General Materials Science ,Electrical and Electronic Engineering ,Crystallization ,Composite material ,Elastic modulus ,Nanocomposite ,Mechanical Engineering ,General Chemistry ,Nanoindentation ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Mechanics of Materials ,Boron nitride ,0210 nano-technology - Abstract
Polyethylene terephthalate-based nanocomposites with hexagonal boron nitride nanosheets (BNNs) were prepared by a solution casting method with varying concentrations of BNNs from 0.5 wt% to 4 wt%. Melting and crystallization behaviour of the composites were investigated by differential scanning calorimetry, which suggests that with increasing presence of nanosheets, the crystallinity increases and hence the polyethylene terephthalate chain mobility gets restricted, which leads to suppression of crystal growth. The nanoindentation measurements on the composite films exhibit improved mechanical properties. Enhancement of 33.3% of elastic modulus and 32.4% of hardness was observed with 2 wt% infusion of boron nitride nanosheets in polyethylene terephthalate.
- Published
- 2020
3. A simple fabrication strategy for orientationally accurate twisted heterostructures
- Author
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Rabindra Biswas, Arindam Ghosh, Shaili Sett, Varun Raghunathan, and Rahul Debnath
- Subjects
Materials science ,Misorientation ,business.industry ,Mechanical Engineering ,Superlattice ,Metamaterial ,Bioengineering ,Heterojunction ,General Chemistry ,law.invention ,symbols.namesake ,Mechanics of Materials ,law ,symbols ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,Scanning tunneling microscope ,van der Waals force ,Electronic band structure ,Raman spectroscopy ,business - Abstract
Van der Waals (vdW) heterostructure is a type of metamaterial where multiple layers of 2D materials are vertically aligned at controlled misorientation. The relative rotation in between the adjacent layers, or the twist angle between them plays a crucial role in changing the electronic band structure of the superlattice. The assembly of multi-layers of precisely twisted two dimensional layered materials requires knowledge of the atomic structure at the edge of the flake. It may be artificially created by the ‘tear and stack’ process. Otherwise, the crystallographic orientation needs to be determined through invasive processes such as transmission electron microscopy or scanning tunneling microscopy, and via second-harmonic generation (SHG). Here, we demonstrate a simple and elegant transfer protocol using only an optical microscope as a edge identifier tool through which, controlled transfer of twisted homobilayer and heterobilayer transition metal dichalcogenides is performed with close to 100% yield. The fabricated twisted vdW heterostructures have been characterized by SHG, Raman spectroscopy and photoluminiscence spectroscopy, confirming the desired twist angle within ∼0.5° accuracy. The presented method is reliable, quick and prevents the use of invasive tools which is desirable for reproducible device functionalities.
- Published
- 2021
4. Percolative switching in transition metal dichalcogenide field-effect transistors at room temperature
- Author
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Arindam Ghosh, Tathagata Paul, and Subhamoy Ghatak
- Subjects
Electron mobility ,Materials science ,FOS: Physical sciences ,Bioengineering ,02 engineering and technology ,Conductivity ,010402 general chemistry ,01 natural sciences ,Noise (electronics) ,law.invention ,Condensed Matter::Materials Science ,law ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,General Materials Science ,Electrical and Electronic Engineering ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Physics ,Mechanical Engineering ,Transistor ,Doping ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Mechanics of Materials ,Percolation ,Field-effect transistor ,Resistor ,0210 nano-technology - Abstract
We have addressed the microscopic transport mechanism at the switching or `on-off' transition in transition metal dichalcogenide (TMDC) field-effect transistors (FETs), which has been a controversial topic in TMDC electronics, especially at room temperature. With simultaneous measurement of channel conductivity and its slow time-dependent fluctuation (or noise) in ultrathin WSe2 and MoS2 FETs on insulating SiO2 substrates where noise arises from McWhorter-type carrier number fluctuations, we establish that the switching in conventional backgated TMDC FETs is a classical percolation transition in a medium of inhomogeneous carrier density distribution. From the experimentally observed exponents in the scaling of noise magnitude with conductivity, we observe unambiguous signatures of percolation in a random resistor network, particularly, in WSe2 FETs close to switching, which crosses over to continuum percolation at a higher doping level. We demonstrate a powerful experimental probe to the microscopic nature of near-threshold electrical transport in TMDC FETs, irrespective of the material detail, device geometry, or carrier mobility, which can be extended to other classes of 2D material-based devices as well.
- Published
- 2016
5. Optimising graphene visibility in van der Waals heterostructures.
- Author
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Thanmay S Menon, Simli Mishra, Vidhu Catherine Antony, Kiranmayi Dixit, Saloni Kakkar, Tanweer Ahmed, Saurav Islam, Aditya Jayaraman, Kimberly Hsieh, Paritosh Karnatak, and Arindam Ghosh
- Subjects
HETEROSTRUCTURES ,SPECTRAL sensitivity ,VISIBILITY ,GRAPHENE - Abstract
Graphene constitutes one of the key elements in many functional van der Waals heterostructures. However, it has negligible optical visibility due to its monolayer nature. Here we study the visibility of graphene in various van der Waals heterostructures and include the effects of the source spectrum, oblique incidence and the spectral sensitivity of the detector to obtain a realistic model. A visibility experiment is performed at different wavelengths, resulting in a very good agreement with our calculations. This allows us to reliably predict the conditions for better visibility of graphene in van der Waals heterostructures. The framework and the codes provided in this work can be extended to study the visibility of any 2D material within an arbitrary van der Waals heterostructure. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
6. Percolative switching in transition metal dichalcogenide field-effect transistors at room temperature.
- Author
-
Tathagata Paul, Subhamoy Ghatak, and Arindam Ghosh
- Subjects
TRANSITION metal compounds ,FIELD-effect transistors ,ELECTRONICS ,ELECTRIC conductivity ,PERCOLATION ,PERCOLATION theory - Abstract
We have addressed the microscopic transport mechanism at the switching or ‘on–off’ transition in transition metal dichalcogenide (TMDC) field-effect transistors (FETs), which has been a controversial topic in TMDC electronics, especially at room temperature. With simultaneous measurement of channel conductivity and its slow time-dependent fluctuation (or noise) in ultrathin WSe
2 and MoS2 FETs on insulating SiO2 substrates where noise arises from McWhorter-type carrier number fluctuations, we establish that the switching in conventional backgated TMDC FETs is a classical percolation transition in a medium of inhomogeneous carrier density distribution. From the experimentally observed exponents in the scaling of noise magnitude with conductivity, we observe unambiguous signatures of percolation in a random resistor network, particularly, in WSe2 FETs close to switching, which crosses over to continuum percolation at a higher doping level. We demonstrate a powerful experimental probe to the microscopic nature of near-threshold electrical transport in TMDC FETs, irrespective of the material detail, device geometry, or carrier mobility, which can be extended to other classes of 2D material-based devices as well. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
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