Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)

The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.Comment: 139 pages, Physics White Paper of the ICAL (INO) Collaboration, Contents identical with the version published in Pramana - J. Physic

Low Buffer Trapping Effects above 1200 V in Normally off GaN-on-Silicon Field Effect Transistors

International audienceWe report on the fabrication and electrical characterization of AlGaN/GaN normally off transistors on silicon designed for high-voltage operation. The normally off configuration was achieved with a p-gallium nitride (p-GaN) cap layer below the gate, enabling a positive threshold voltage higher than +1 V. The buffer structure was based on AlN/GaN superlattices (SLs), delivering a vertical breakdown voltage close to 1.5 kV with a low leakage current all the way to 1200 V. With the grounded substrate, the hard breakdown voltage transistors at VGS = 0 V is 1.45 kV, corresponding to an outstanding average vertical breakdown field higher than 2.4 MV/cm. High-voltage characterizations revealed a state-of-the-art combination of breakdown voltage at VGS = 0 V together with low buffer electron trapping effects up to 1.4 kV, as assessed by means of substrate ramp measurements

Investigation on GaN channel thickness downscaling in high electron mobility transistor structures grown on AlN bulk substrate

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AlGaN channel high electron mobility transistors with regrown ohmic contacts

International audienceHigh power electronics using wide bandgap materials are maturing rapidly, and significantmarket growth is expected in a near future. Ultra wide bandgap materials, which have an even largerbandgap than GaN (3.4 eV), represent an attractive choice of materials to further push the performancelimits of power devices. In this work, we report on the fabrication of AlN/AlGaN/AlN high-electronmobility transistors (HEMTs) using 50% Al-content on the AlGaN channel, which has a much widerbandgap than the commonly used GaN channel. The structure was grown by metalorganic chemicalvapor deposition (MOCVD) on AlN/sapphire templates. A buffer breakdown field as high as5.5 MV/cm was reported for short contact distances. Furthermore, transistors have been successfullyfabricated on this heterostructure, with low leakage current and low on-resistance. A remarkablethree-terminal breakdown voltage above 4 kV with an off-state leakage current below 1μA/mm wasachieved. A regrown ohmic contact was used to reduce the source/drain ohmic contact resistance,yielding a drain current density of about 0.

Evaluation of Self-Heating Effects in AlGaN Channel Heterostructure field-effect Transistors grown on bulk AlN substrate

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Effects of GaN channel downscaling in AlGaN–GaN high electron mobility transistor structures grown on AlN bulk substrate

International audienceIn this work, two series of AlGaN/GaN/AlN high electron mobility transistor (HEMT) heterostructures have been grown by molecular beam epitaxy on AlN bulk substrates. The effects of reduction in the GaN channel thickness as well as the AlGaN barrier thickness and composition on structural and electrical properties of the heterostructures have been studied. The material analysis involved high-resolution x-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy. In a first series of HEMT structures grown with an aluminum content of 30% in the AlGaN barrier, the channel downscaling results in a reduction in the GaN strain relaxation rate but at the expense of degradation in the mean crystal quality and in the electron mobility with a noticeable increase in the sheet resistance. An opposite trend is noticed for the three-terminal breakdown voltage of transistors, so that a trade-off is obtained for a 50 nm width GaN channel HEMT, which exhibits a sheet resistance of 1700 Ω/sq. with transistors demonstrating three-terminal breakdown voltage up to 1400 V for 40 μm gate to drain spacing with static on resistance R on = 32 mΩ cm 2 . On the other hand, a second series of HEMT structures with high aluminum content AlGaN barriers and sub-10 nm GaN channels have been grown perfectly strained with high sheet carrier densities allowing to preserve sheet resistances in the range of 880–1050 Ω/sq

Towards high buffer breakdown field and high temperature stability AlGaN channel HEMTs on silicon substrate

International audienceThe rapidly increasing power demand, downsizing of power electronics and material specific performance limitation of silicon has led to the development of AlGaN/GaN heterostructures for high power applications. In this frame, emerging AlxGa1-xN channel based heterostructures show promising features for next generation of power electronics. In this work, we propose the study of breakdown field variation through the AlGaN channel HEMTs-on-Silicon with various Al composition. The fabricated devices exhibited remarkable buffer breakdown field > 2.5 MV/cm for sub-micron heterostructures grown on silicon substrate. Furthermore, we also experimentally demonstrate that Al-rich AlGaN channel enable both boosting the 3-terminal transistor breakdown voltage and also benefiting from a superior thermal stability

jashgopani/slash: Slash Phase 4

<h2>What's Changed</h2> <ul> <li>Updated UI - <a href="https://github.com/jashgopani/slash-frontend">https://github.com/jashgopani/slash-frontend</a></li> <li>Made the project lightweight by removing unnecessary files</li> <li>Updated and easy to understand documentation</li> </ul> <h2>New Contributors</h2> <ul> <li>@rohanajm7 made their first contribution in https://github.com/jashgopani/slash/pull/7</li> <li>@jashgopani made their first contribution in https://github.com/jashgopani/slash/pull/8</li> <li>@neerua08 made their first contribution in https://github.com/jashgopani/slash/pull/9</li> </ul> <p><strong>Full Changelog</strong>: https://github.com/jashgopani/slash/compare/v1.1.4...v2.0.0</p&gt

Real-time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device

Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real-time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time-course data for bulk and peri-cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non-invasive and label-free approach. Additionally, we confirmed non-invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell(-1) s(-1) , and 5 and 35 amol cell(-1) s(-1) were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non-invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell-based therapies