Search

Your search keyword '"Srinivasan Raghavan"' showing total 31 results
Start Over Author "Srinivasan Raghavan" Publisher springer science and business media llc
31 results on '"Srinivasan Raghavan"'

7. Evaluation of gridded meteorological datasets and their potential hydrological application to a humid area with scarce data for Pirapama River basin, northeastern Brazil

Author

Viana, Jussara Freire de Souza, primary, Montenegro, Suzana Maria Gico Lima, additional, da Silva, Bernardo Barbosa, additional, da Silva, Richarde Marques, additional, Srinivasan, Raghavan, additional, Santos, Celso Augusto Guimarães, additional, Araujo, Diego Cezar dos Santos, additional, and Tavares, Clara Gadelha, additional

Published
2021
Full Text
View/download PDF

10. Graphene–MoS2 hybrid structures for multifunctional photoresponsive memory devices

Author

Srijit Goswami, Gopalakrishnan Ramalingam, T. Phanindra Sai, Arindam Ghosh, Medini Padmanabhan, Srinivasan Raghavan, and Kallol Roy

Subjects
Materials science, Graphene, business.industry, Band gap, Materials Research Centre, Physics, Relaxation (NMR), Biomedical Engineering, Photodetector, Bioengineering, Heterojunction, Nanotechnology, Photodetection, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, law.invention, Responsivity, Photosensitivity, law, Centre for Nano Science and Engineering, Optoelectronics, General Materials Science, Electrical and Electronic Engineering, business
Abstract

Combining the electronic properties of graphene(1,2) and molybdenum disulphide (MoS2)(3-6) in hybrid heterostructures offers the possibility to create devices with various functionalities. Electronic logic and memory devices have already been constructed from graphene-MoS2 hybrids(7,8), but they do not make use of the photosensitivity of MoS2, which arises from its optical-range bandgap(9). Here, we demonstrate that graphene-on-MoS2 binary heterostructures display remarkable dual optoelectronic functionality, including highly sensitive photodetection and gate-tunable persistent photoconductivity. The responsivity of the hybrids was found to be nearly 1 x 10(10) A W-1 at 130 K and 5 x 10(8) A W-1 at room temperature, making them the most sensitive graphene-based photodetectors. When subjected to time-dependent photoillumination, the hybrids could also function as a rewritable optoelectronic switch or memory, where the persistent state shows almost no relaxation or decay within experimental timescales, indicating near-perfect charge retention. These effects can be quantitatively explained by gate-tunable charge exchange between the graphene and MoS2 layers, and may lead to new graphene-based optoelectronic devices that are naturally scalable for large-area applications at room temperature.

Published
2013
Full Text
View/download PDF

14. Stress and Phase Engineered ZrO2/Ge for High-k Dielectric Applications

Author

Amiya Banerjee, Narayan K. V. L.V. Achari, and Srinivasan Raghavan

Subjects
Stress (mechanics), Materials science, business.industry, Phase (matter), Optoelectronics, Grain boundary, Cubic zirconia, Dielectric, Sputter deposition, Thin film, business, High-κ dielectric
Abstract

ZrO2/Ge is potential high-k dielectric candidate to replace silicon based devices. Controlling stress in zirconia film and stabilizing high dielectric constant phase is crucial for high-k application. A precise control of stress and phase selectivity in high-k thin films is demonstrated. Thin films of ZrO2 were grown by reactive sputter deposition. Wide range of growth stress in thin films from -0.3 to -2.8 GPa can be tuned by growth rate control. Adatom incorporation into grain boundary was the dominant source of observed stress. Phase selectivity in zirconia was achieved by tuning growth parameters.

Published
2015
Full Text
View/download PDF

17. Optoelectronic properties of graphene-MoS2 hybrid

Author

Srinivasan Raghavan, Srijit Goswami, Sanjeev Kaushal, Kallol Roy, Arindam Ghosh, Gopalakrishnan Ramalingam, Medini Padmanabhan, and T. Phanindra Sai

Subjects
Materials science, business.industry, Graphene, law, Photoconductivity, White light, Optoelectronics, Chemical vapor deposition, business, Gate voltage, law.invention
Abstract

Ultra-thin flakes of layered materials have recently been attracting widespread research interest due to their exotic properties. In this work, we study the optoelectronic response of a hybrid of two such materials – graphene and MoS2. Our devices consist of mechanically exfoliated graphene flakes transferred on top of similarly exfoliated MoS2. The electrical response of the hybrid is studied in the presence of white light. We show that the four-point resistance of graphene is modulated in the presence of light. This effect is observed to be a strong function of gate voltage. We have also extended our studies to CVD (chemical vapor deposition) - grown graphene transferred onto MoS2 which show qualitatively similar features, thereby attesting to the scalability of the device architecture.

Published
2013
Full Text
View/download PDF

19. Stress and Microstructure Evolution in Compositionally Graded Al1-xGaxN Buffer Layers for GaN Growth on Si

Author

Elizabeth C. Dickey, Joan M. Redwing, Srinivasan Raghavan, and Xiaojun Weng

Subjects
Stress (mechanics), Crystallography, Compressive strength, Materials science, Transmission electron microscopy, Dislocation, Composite material, Nitride, Microstructure, Layer (electronics), Buffer (optical fiber)
Abstract

We have studied the evolution of stress and microstructure of compositionally graded Al1-xGaxN (0 ≤ x ≤1) buffer layers on (111) Si substrates with varying thicknesses. In-situ stress measurements reveal a tensile-to-compressive stress transition that occurs near the half-thickness in each buffer layer. Cross-sectional transmission electron microscopy (TEM) shows a significant reduction in threading dislocation (TD) density in the top half of the buffer layer, suggesting that the compressive stress enhances the threading dislocation annihilation. The composition of the buffer layers varies linearly with thickness, as determined by X-ray energy dispersive spectrometry (XEDS). The composition grading-induced compressive stress offsets the tensile stress introduced by microstructure evolution, thus yielding a tensile-to-compressive stress transition at x ≈ 0.5.

Published
2005
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results