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Mahesh Kumar

Bio: Mahesh Kumar is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Molecular beam epitaxy & Heterojunction. The author has an hindex of 29, co-authored 204 publications receiving 4864 citations. Previous affiliations of Mahesh Kumar include Indian Institutes of Technology & Indian Institute of Technology Delhi.


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TL;DR: In this article, the authors introduce the recent trends in heavy metal ion sensing with semiconductor devices, including ion-sensitive field effect transistors (ISFETs) and AlGaN/GaN high electron mobility transistors(HEMTs) and semiconductor materials like graphene, two-dimensional metal dichalcogenides, decorated with different nanoparticles with appropriate functionalization.
Abstract: Heavy metal ions are highly toxic, carcinogens, and non-biodegradable in nature and pollute most water resources that lead to severe health-related issues. It is essential to develop highly sensitive, selective, rapid, and accurate approaches for their detection in water. Semiconducting devices and materials with micro and nanostructures have been featured with fast response time, low power, high sensitivity, low detection limit. This review concisely introduces the recent trends in heavy metal ion sensing with semiconductor devices, including ion-sensitive field-effect transistors (ISFETs) and AlGaN/GaN high electron mobility transistors (HEMTs) and semiconductor materials like graphene, two-dimensional metal dichalcogenides, decorated with different nanoparticles with appropriate functionalization.

20 citations

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TL;DR: In this paper, a xenon-filled coaxial dielectric barrier discharge (DBD) has been studied to understand the high-pressure nonequilibrium nonthermal plasma discharge.
Abstract: In this paper, a xenon-filled coaxial dielectric barrier discharge (DBD) has been studied to understand the high-pressure nonequilibrium nonthermal plasma discharge. A quartz coaxial DBD tube (ID: 6 mm, OD: 12 mm) at 400-mbar xenon-filled pressure has been used in the experiment. A unipolar pulselike voltage up to a-6-kV peak working at 30 kHz has been applied to the discharge electrodes for the generation of microdischarges. A single discharge is observed per applied voltage pulse. Visual images of the discharge and electrical waveform confirm the diffused-type discharges. The knowledge obtained by dynamic processes of DBDs in the discharge gap explains quantitatively the mechanism that is obtained in the ignition, development, and extinction of DBDs. The behavior of different discharge parameters has also been analyzed. From the experimental results and equivalent electrical circuit, the dynamic nature of equivalent capacitance has been reported. The relative intensity analysis of the Xe peak in the optical emission spectra (172 nm) has also been carried out for different supplied powers, and it is found that the radiation power has increased with supplied power.

20 citations

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Morteza Aghaee, Arun Goud Akkala, Zulfiqar Alam, Rizwan Ali, Alejandro Ramirez, Mariusz Andrzejczuk, Andrey E. Antipov, Pavel Aseev, Mikhail A. Astafev, Bela Bauer, J. Becker, Srinivasa Rao Boddapati, Frenk Boekhout, Jouri D. S. Bommer, E. B. Hansen, Tom Bosma, L. Bourdet, Samuel Boutin, Philippe Caroff, Lucas Casparis, Maja C. Cassidy, Anna Wulff Christensen, Noah Clay, William S. Cole, Fabiano Corsetti, Ajuan Cui, Paschalis Dalampiras, Anand Dokania, G. de Lange, Michiel W. A. de Moor, J. C. Estrada Saldaña, Saeed Fallahi, Zahra Heidarnia Fathabad, John King Gamble, Geoffrey C. Gardner, Deshanie Govender, Flavio Griggio, Ruben Grigoryan, Sergei Gronin, Jan Gukelberger, Sebastian Heedt, Jesús Herranz Zamorano, Samantha Ho, U. Laurens D. Holgaard, William H. P. Nielsen, Henrik Ingerslev, Peter Krogstrup, Linda I. M. Johansson, Jeffrey Jones, Ray Kallaher, Farhad Karimi, Torsten Karzig, Cameron N. King, Maren E. Kloster, Christina Knapp, D. Kocon, Jonne V. Koski, Pasi Kostamo, Mahesh Kumar, Tom Laeven, T. W. Larsen, Kongyi Li, Tyler Lindemann, Julie Helen Love, Roman M. Lutchyn, Michael J. Manfra, Elvedin Memisevic, Chetan Nayak, Bas Nijholt, Morten Hannibal Madsen, Signe B. Markussen, E. A. Martínez, Robert McNeil, Andrew Mullally, Jens H. Nielsen, Anne Nurmohamed, Eoin O'Farrell, Keita Otani, S. J. Pauka, Karl Petersson, L. Petit, Dima Pikulin, Frank Santa Cruz Preiss, Marina Quintero Perez, Katrine Skovgaard Rasmussen, Mohana K. Rajpalke, Davydas Razmadze, Outi Reentila, David J. Reilly, Richard Rouse, Ivan Sadovskyy, Lauri Sainiemi, Sydney Schreppler, V. G. Sidorkin, Amrita Singh, Shilpi Singh, S.P. Sinha, Patrick Sohr, Tomavs Stankevivc, Lieuwe J Stek, Henri J. Suominen, Judith Suter, V. N. Svidenko, Samuel M. L. Teicher, Mine Temuerhan, Nivetha Thiyagarajah, R. Tholapi, Mason Thomas, Emily Toomey, Shivendra Upadhyay, Ivica Urban, S. Vaitiek.enas, Kevin Van Hoogdalem, D V Viazmitinov, S. J. Waddy, D. J. van Woerkom, Dominik Vogel, John Watson, Joseph Weston, Georg W. Winkler, Chung-Kai Yang, Sean Shun Ming Yau, Daniel Choong Zhi Yi, E. Yucelen, A. Webster, Roland Zeisel, Ruichen Zhao 
TL;DR: In this article , the authors present measurements and simulations of semiconductor-superconductor heterostructure devices that are consistent with the observation of topological superconductivity and Majorana zero modes.
Abstract: We present measurements and simulations of semiconductor-superconductor heterostructure devices that are consistent with the observation of topological superconductivity and Majorana zero modes. The devices are fabricated from high-mobility two-dimensional electron gases in which quasi-one-dimensional wires are defined by electrostatic gates. These devices enable measurements of local and non-local transport properties and have been optimized via extensive simulations to ensure robustness against non-uniformity and disorder. Our main result is that several devices, fabricated according to the design's engineering specifications, have passed the topological gap protocol defined in Pikulin \textit{et al.} [arXiv:2103.12217]. This protocol is a stringent test composed of a sequence of three-terminal local and non-local transport measurements performed while varying the magnetic field, semiconductor electron density, and junction transparencies. Passing the protocol indicates a high probability of detection of a topological phase hosting Majorana zero modes as determined by large-scale disorder simulations. Our experimental results are consistent with a quantum phase transition into a topological superconducting phase that extends over several hundred millitesla in magnetic field and several millivolts in gate voltage, corresponding to approximately one hundred micro-electron-volts in Zeeman energy and chemical potential in the semiconducting wire. These regions feature a closing and re-opening of the bulk gap, with simultaneous zero-bias conductance peaks at \textit{both} ends of the devices that withstand changes in the junction transparencies. The extracted maximum topological gaps in our devices are 20-$60\,\mu$eV. This demonstration is a prerequisite for experiments involving fusion and braiding of Majorana zero modes.

19 citations

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TL;DR: In this article, the authors determined the band offsets in InN/p-Si heterojunctions by high-resolution x-ray photoemission spectroscopy, finding that the valence band of InN is 1.39 eV below that of Si.
Abstract: The band offsets in InN/p-Si heterojunctions are determined by high resolution x-ray photoemission spectroscopy. The valence band of InN is found to be 1.39 eV below that of Si. Given the bandgap of 0.7 eV for InN, a type-III heterojunction with a conduction band offset of 1.81 eV was found. Agreement between the simulated and experimental data obtained from the heterojunction spectra was found to be excellent, establishing that the method of determination was accurate. The charge neutrality level (CNL) model provided a reasonable description of the band alignment of the InN/p-Si interface and a change in the interface dipole by 0.06 eV was observed for InN/p-Si interface.

19 citations

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TL;DR: Improved NO2 gas sensing properties based on reduced graphene oxide (rGO) decorated V2O5 thin film is demonstrated and the presence of active sites like oxygenous functional groups on the rGO surface enhanced the sensing response.
Abstract: Here, we demonstrate improved NO2 gas sensing properties based on reduced graphene oxide (rGO) decorated V2O5 thin film. Excluding the DC sputtering grown V2O5 thin film, rGO was spread over V2O5 thin film by the drop cast method. The formation of several p-n heterojunctions was greatly affected by the current-voltage relation of the rGO-decorated V2O5 thin film due to the p-type and n-type nature of rGO and V2O5, respectively. Initially with rGO decoration on V2O5 thin film, current decreased in comparison to the pristine V2O5 thin film, whereas depositing rGO film on a glass substrate drastically increased current. Among all sensors, only the rGO-decorated V2O5 sensor revealed a maximum NO2 gas sensing response for 100 ppm at 150 °C, and it achieved an approximately 61% higher response than the V2O5 sensor. The elaborate mechanism for an extremely high sensing response is attributed to the formation and modulation of p-n heterojunctions at the interface of rGO and V2O5. In addition, the presence of active sites like oxygenous functional groups on the rGO surface enhanced the sensing response. On that account, sensors based on rGO-decorated V2O5 thin film are highly suitable for the purpose of NO2 gas sensing. They enable the timely detection of the gas, further protecting the ecosystem from its harmful effects.

19 citations


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7,335 citations

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TL;DR: In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented, ranging from atom to phase diagram, and the current development stage in lead free piezoceramics is then critically assessed.
Abstract: A large body of work has been reported in the last 5 years on the development of lead-free piezoceramics in the quest to replace lead–zirconate–titanate (PZT) as the main material for electromechanical devices such as actuators, sensors, and transducers. In specific but narrow application ranges the new materials appear adequate, but are not yet suited to replace PZT on a broader basis. In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented. Suitable chemical elements are selected first on the basis of cost and toxicity as well as ionic polarizability. Different crystal structures with these elements are then considered based on simple concepts, and a variety of phase diagrams are described with attractive morphotropic phase boundaries, yielding good piezoelectric properties. Finally, lessons from density functional theory are reviewed and used to adjust our understanding based on the simpler concepts. Equipped with these guidelines ranging from atom to phase diagram, the current development stage in lead-free piezoceramics is then critically assessed.

2,510 citations

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TL;DR: In this article, a single-phased ferroelectromagnet BiFeO3 ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique.
Abstract: Single-phased ferroelectromagnet BiFeO3 ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 °C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 μC/cm2, 4.0 μC/cm2, and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of Fe2+ and an oxygen deficiency leading to the higher leakage can be greatly suppressed by the very high heating rate, short sintering period, and liquid phase sintering technique. The latter was also found effective in increasing the density of the ceramics. The sintering technique developed in this work is expected to be useful in synthesizing other ceramics from multivalent or volatile starting materials.

970 citations

Journal ArticleDOI
Ling Zhu1, Wen Zeng1
TL;DR: In this paper, the room-temperature gas sensing properties of ZnO-based gas sensors are comprehensively reviewed, and more attention is particularly paid to the effective strategies that create room temperature gas sensing, mainly including surface modification, additive doping and light activation.
Abstract: Novel gas sensors with high sensing properties, simultaneously operating at room temperature are considerably more attractive owing to their low power consumption, high security and long-term stability. Till date, zinc oxide (ZnO) as semiconducting metal oxide is considered as the promising resistive-type gas sensing material, but elevated operating temperature becomes the bottleneck of its extensive applications in the field of real-time gas monitoring, especially in flammable and explosive gas atmosphere. In this respect, worldwide efforts have been devoted to reducing the operating temperature by means of multiple methods In this communication, room-temperature gas sensing properties of ZnO based gas sensors are comprehensively reviewed. Much more attention is particularly paid to the effective strategies that create room-temperature gas sensing of ZnO based gas sensors, mainly including surface modification, additive doping and light activation. Finally, some perspectives for future investigation on room-temperature gas-sensing materials are discussed as well.

756 citations