Author
Ashok Kumar
Other affiliations: University of Delhi, Shobhit University, Vidya College of Engineering
Bio: Ashok Kumar is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Materials science & Adsorption. The author has an hindex of 3, co-authored 13 publications receiving 31 citations. Previous affiliations of Ashok Kumar include University of Delhi & Shobhit University.
Topics: Materials science, Adsorption, Nanoparticle, Nanotechnology, Medicine
Papers
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TL;DR: In this paper, the status of ion implantation in β-Ga2O3 is reviewed and the results of experimental study of damage under ion irradiation and the properties of Ga 2O3 layers doped by ion implantations are discussed.
Abstract: Gallium oxide, and in particular its thermodynamically stable β-Ga2O3 phase, is within the most exciting materials in research and technology nowadays due to its unique properties The very high breakdown electric field and the figure of merit rivaled only by diamond have tremendous potential for the next generation “green” electronics enabling efficient distribution, use, and conversion of electrical energy Ion implantation is a traditional technological method used in these fields, and its well-known advantages can contribute greatly to the rapid development of physics and technology of Ga2O3-based materials and devices Here, the status of ion implantation in β-Ga2O3 nowadays is reviewed Attention is mainly paid to the results of experimental study of damage under ion irradiation and the properties of Ga2O3 layers doped by ion implantation The results of ab initio theoretical calculations of the impurities and defect parameters are briefly presented, and the physical principles of a number of analytical methods used to study implanted gallium oxide layers are highlighted The use of ion implantation in the development of Ga2O3-based devices, such as metal oxide field-effect transistors, Schottky barrier diodes, and solar-blind UV detectors, is described together with systematical analysis of the achieved values of their characteristics Finally, the most important challenges to be overcome in this field of science and technology are discussed
37 citations
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TL;DR: In this paper, a review of reduced graphene oxide (rGO) based photodetectors is presented, which provides a much-needed timely update and future prospects to the scientific community.
Abstract: Reduced graphene oxide (rGO) has tunable properties and acts as an efficient low-cost alternative for graphene in many applications. It also has its own exciting electronic and optoelectronic characteristics. The properties of rGO can be altered by tuning the amount of reduction, types of defects, doping and functionalization. The reduction of graphene oxide (GO) by various methods and the large-scale production of rGO can be easily achieved. These properties led the research drive for low-cost and high-end applications of rGO-based devices. It has found applications in almost all branches of applied science and engineering. Recent research works show that rGO-based photodetectors achieved high responsivity and detectivity values with fast operation speed. Although there are many reviews on graphene-based photodetectors, there has been much less focus on rGO-based photodetectors. In this review, we focus on rGO-based photodetectors, photodetection mechanism and advancements in the field. Thus, in this review, we provide a much-needed timely update and future prospects to the scientific community.
16 citations
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01 Mar 2012-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, the registration sensitivity of very low energy proton in CR-39 is investigated and the bulk and track etch rates were measured by using proton track diameters.
Abstract: In this paper threshold of the registration sensitivity of very low energy proton in CR-39 is investigated. Irradiation of CR-39 (poly-allyl-diglycol carbonate) was carried out with very low energy mono energetic protons of 20–60 keV from a mini proton accelerator. Nearly 104/cm2 fluence of protons was used. The variation of track diameter with etching time as well as proton energy response curve was carefully calibrated. The bulk and track etch rates were measured by using proton track diameters. Bulk etch rate was also measured by the thickness of removed surface layer. The thermal annealing of proton track at temperatures ranging from 100 to 200 °C in CR-39 was studied by several models. Activation energy of annealed CR-39 detectors was calculated by slope of track etch rate and temperature plot. The data of proton tracks of 200, 250 and 300 keV from 400 kV Van-de-Graaff accelerator was also used and compared with the track diameters of different energies of proton.
13 citations
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TL;DR: In this paper, a highly selective and sensitive NO2 gas sensor using vertically aligned 2D SnS2 flakes, grown by a chemical vapor deposition method in controlled gas flow, was demonstrated.
Abstract: Two dimensional chalcogenides and metal sulfide materials with their sensitive surfaces are promising and potential postulant for the purpose of chemical gas sensing as a consequence of extraordinary vast surface area to volume ratio and significant band gap. We demonstrate a highly selective and sensitive NO2 gas sensor using vertically aligned 2D SnS2 flakes, grown by a chemical vapor deposition method in controlled gas flow. The vertically aligned SnS2 flakes were confirmed by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. The sensing behaviour of the vertical aligned structures was analyzed for various concentrations of NO2 at different temperatures. The sensor exhibits high gas sensing response (ΔR/R%) of ~164 at 120 °C with 50 ppm of NO2 gas, which is the highest response among the SnS2 based reports. The device shows excellent sensing response at room temperature but poor recovery. The selectivity of the sensor was performed under different gas environments and found highly selective towards NO2 gas, and the results are supported by electronic structure calculations. Based on experimental results and electronic structure calculations, a gas sensing mechanism is proposed. The result indicates that fabricated sensor can be used in air purification industries and in air monitoring.
12 citations
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TL;DR: In this paper, the authors have studied the bulk etching rate and track etch rate before and after gamma-ray irradiation on Lexan and Makrofol-DE polycarbonate plastics.
Abstract: It is observed that for Lexan and Makrofol-DE polycarbonate plastic detectors the mean diameters of fission fragments from a 252Cf source increases as a result of gamma-ray exposure We have studied the bulk etching rate and track etching rate before and after gamma-ray irradiation on Lexan and Makrofol-DE polycarbonate plastics The mechanism of Lexan and Makrofol-DE polycarbonate plastic detectors can be understood with the help of this exposures It is also noted that degree of ordering of Lexan and Makrofol-DE polycarbonate is dependent on the gamma ray dose due to degradation and cross-linking processes The results show that bulk and track etch rate increases with gamma dose while activation energy associated with bulk and track etch rates at a particular temperature and sensitivity decreases with gamma dose
11 citations
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TL;DR: In this paper, nuclear tracks in solids (Principles and Applications) nuclear technology: Vol. 30, No. 1, pp. 91-92, were discussed and discussed in detail.
Abstract: (1976). Nuclear Tracks in Solids (Principles and Applications) Nuclear Technology: Vol. 30, No. 1, pp. 91-92.
973 citations
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TL;DR: In this paper, the ultrafast relaxation and recombination dynamics of photogenerated electrons and holes in epitaxial graphene were studied using optical-pump Terahertz-probe spectroscopy.
Abstract: The ultrafast relaxation and recombination dynamics of photogenerated electrons and holes in epitaxial graphene are studied using optical-pump Terahertz-probe spectroscopy. The conductivity in graphene at Terahertz frequencies depends on the carrier concentration as well as the carrier distribution in energy. Time-resolved studies of the conductivity can therefore be used to probe the dynamics associated with carrier intraband relaxation and interband recombination. We report the electron-hole recombination times in epitaxial graphene for the first time. Our results show that carrier cooling occurs on sub-picosecond time scales and that interband recombination times are carrier density dependent.
508 citations
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TL;DR: In this article , a comprehensive review of representative 2D materials, general fabrication methods, and characterization techniques and the vital role of the physical parameters affecting the quality of 2D heterostructures are discussed.
Abstract: A grand family of two-dimensional (2D) materials and their heterostructures have been discovered through the extensive experimental and theoretical efforts of chemists, material scientists, physicists, and technologists. These pioneering works contribute to realizing the fundamental platforms to explore and analyze new physical/chemical properties and technological phenomena at the micro-nano-pico scales. Engineering 2D van der Waals (vdW) materials and their heterostructures via chemical and physical methods with a suitable choice of stacking order, thickness, and interlayer interactions enable exotic carrier dynamics, showing potential in high-frequency electronics, broadband optoelectronics, low-power neuromorphic computing, and ubiquitous electronics. This comprehensive review addresses recent advances in terms of representative 2D materials, the general fabrication methods, and characterization techniques and the vital role of the physical parameters affecting the quality of 2D heterostructures. The main emphasis is on 2D heterostructures and 3D-bulk (3D) hybrid systems exhibiting intrinsic quantum mechanical responses in the optical, valley, and topological states. Finally, we discuss the universality of 2D heterostructures with representative applications and trends for future electronics and optoelectronics (FEO) under the challenges and opportunities from physical, nanotechnological, and material synthesis perspectives.
85 citations
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TL;DR: In this article, the UV-visible absorption spectra of virgin and alpha particle-irradiated, annealed and non-annealed CR-39 polymeric track detectors were investigated using a Shimadzu mini 1240 spectrometer.
25 citations
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TL;DR: The sensitivity of charged particle registration with SSNTD is the most important parameter to decide about the applicability of those detectors in research, technology and environmental dosimetry as discussed by the authors.
24 citations