The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Nicolas Agrait - One of the best experts on this subject based on the ideXlab platform.
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High Current Density electrical breakdown of tis3 nanoribbon based field effect transistors
arXiv: Mesoscale and Nanoscale Physics, 2017Co-Authors: Aday J Molinamendoza, Joshua O Island, Wendel S Paz, Jose M Clamagirand, J R Ares, Eduardo Flores, F Leardini, C Sanchez, Nicolas AgraitAbstract:The High field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, we study here the High Current Density properties of the layered material titanium trisulfide (TiS3). We observe High breakdown Current densities up to 1.7 10^6 A/cm^2 in TiS3 nanoribbon-based field-effect transistors which are among the Highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for Current breakdown, we perform a thermogravimetric analysis of bulk TiS3 and compare the results with Density functional theory (DFT) and Kinetic Monte Carlo calculations. We conclude that oxidation of TiS3 and subsequent desorption of sulfur atoms plays an important role in the electrical breakdown of the material in ambient conditions. Our results show that TiS3 is an attractive material for High power applications and lend insight to the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.
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High Current Density electrical breakdown of tis3 nanoribbon based field effect transistors
Advanced Functional Materials, 2017Co-Authors: Aday J Molinamendoza, Joshua O Island, Wendel S Paz, Jose M Clamagirand, J R Ares, Eduardo Flores, F Leardini, C Sanchez, Nicolas AgraitAbstract:The High field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, the High Current Density properties of the layered material titanium trisulfide (TiS3) are studied here. The High breakdown Current densities of up to 1.7 × 106 A cm−2 are observed in TiS3 nanoribbon-based field-effect transistors, which are among the Highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for Current breakdown, a thermogravimetric analysis of bulk TiS3 is performed and the results with Density functional theory and kinetic Monte Carlo calculations are compared. In conclusion, the oxidation of TiS3 and subsequent desorption of sulfur atoms play an important role in the electrical breakdown of the material in ambient conditions. The results show that TiS3 is an attractive material for High power applications and lend insight into the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.
Huiming Cheng - One of the best experts on this subject based on the ideXlab platform.
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High throughput production of cheap mineral based two dimensional electrocatalysts for High Current Density hydrogen evolution
Nature Communications, 2020Co-Authors: Chi Zhang, Yuting Luo, Junyang Tan, Fengning Yang, Zhiyuan Zhang, L X Yang, Huiming Cheng, Bilu LiuAbstract:The High-throughput scalable production of cheap, efficient and durable electrocatalysts that work well at High Current densities demanded by industry is a great challenge for the large-scale implementation of electrochemical technologies. Here we report the production of a two-dimensional molybdenum disulfide-based ink-type electrocatalyst by a scalable exfoliation technique followed by a thermal treatment. The catalyst delivers a High Current Density of 1000 mA cm−2 at an overpotential of 412 mV for the hydrogen evolution. Using the same method, we produce a cheap mineral-based catalyst possessing excellent performance for High-Current-Density hydrogen evolution. Noteworthy, production rate of this catalyst is one to two orders of magnitude Higher than those previously reported, and price of the mineral is five orders of magnitude lower than commercial Pt electrocatalysts. These advantages indicate the huge potentials of this method and of mineral-based cheap and abundant natural resources as catalysts in the electrochemical industry. The large-scale implementation of electrochemical technologies will require the High-throughput production of High-performance, inexpensive catalysts. Here, authors demonstrate earth abundant molybdenite as raw materials to produce efficient MoS2 catalysts for High Current Density H2 evolution.
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morphology and surface chemistry engineering toward ph universal catalysts for hydrogen evolution at High Current Density
Nature Communications, 2019Co-Authors: Lei Tang, Huiming Cheng, Usman Khan, Qiangmin YuAbstract:Large-scale implementation of electrochemical hydrogen production requires several fundamental issues to be solved, including understanding the mechanism and developing inexpensive electrocatalysts that work well at High Current densities. Here we address these challenges by exploring the roles of morphology and surface chemistry, and develop inexpensive and efficient electrocatalysts for hydrogen evolution. Three model electrocatalysts are flat platinum foil, molybdenum disulfide microspheres, and molybdenum disulfide microspheres modified by molybdenum carbide nanoparticles. The last catalyst is Highly active for hydrogen evolution independent of pH, with low overpotentials of 227 mV in acidic medium and 220 mV in alkaline medium at a High Current Density of 1000 mA cm−2, because of enhanced transfer of mass (reactants and hydrogen bubbles) and fast reaction kinetics due to surface oxygen groups formed on molybdenum carbide during hydrogen evolution. Our work may guide rational design of electrocatalysts that work well at High Current densities. Hydrogen production from water provides one avenue toward harnessing renewable energy, although large-scale implementation remains a challenge. Here, authors explore roles of morphology and surface chemistry, and develop efficient catalysts for hydrogen evolution at High Current densities.
Aday J Molinamendoza - One of the best experts on this subject based on the ideXlab platform.
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High Current Density electrical breakdown of tis3 nanoribbon based field effect transistors
arXiv: Mesoscale and Nanoscale Physics, 2017Co-Authors: Aday J Molinamendoza, Joshua O Island, Wendel S Paz, Jose M Clamagirand, J R Ares, Eduardo Flores, F Leardini, C Sanchez, Nicolas AgraitAbstract:The High field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, we study here the High Current Density properties of the layered material titanium trisulfide (TiS3). We observe High breakdown Current densities up to 1.7 10^6 A/cm^2 in TiS3 nanoribbon-based field-effect transistors which are among the Highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for Current breakdown, we perform a thermogravimetric analysis of bulk TiS3 and compare the results with Density functional theory (DFT) and Kinetic Monte Carlo calculations. We conclude that oxidation of TiS3 and subsequent desorption of sulfur atoms plays an important role in the electrical breakdown of the material in ambient conditions. Our results show that TiS3 is an attractive material for High power applications and lend insight to the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.
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High Current Density electrical breakdown of tis3 nanoribbon based field effect transistors
Advanced Functional Materials, 2017Co-Authors: Aday J Molinamendoza, Joshua O Island, Wendel S Paz, Jose M Clamagirand, J R Ares, Eduardo Flores, F Leardini, C Sanchez, Nicolas AgraitAbstract:The High field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, the High Current Density properties of the layered material titanium trisulfide (TiS3) are studied here. The High breakdown Current densities of up to 1.7 × 106 A cm−2 are observed in TiS3 nanoribbon-based field-effect transistors, which are among the Highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for Current breakdown, a thermogravimetric analysis of bulk TiS3 is performed and the results with Density functional theory and kinetic Monte Carlo calculations are compared. In conclusion, the oxidation of TiS3 and subsequent desorption of sulfur atoms play an important role in the electrical breakdown of the material in ambient conditions. The results show that TiS3 is an attractive material for High power applications and lend insight into the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.
Ji Li - One of the best experts on this subject based on the ideXlab platform.
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Scandate dispenser cathode fabrication for a High-aspect-ratio High-Current-Density sheet beam electron gun
IEEE Transactions on Electron Devices, 2012Co-Authors: Jinfeng Zhao, Mike Banducci, Larry Barnett, Alexander G. Spear, Subhash Risbud, Diana Gamzina, Na Li, Ji Li, Neville C. LuhmannAbstract:A High-Current-Density scandate tungsten dispenser cathode was used for the demonstration of a 25 : 1-aspect-ratio 750-A/cm2-Current-Density sheet beam for the Defence Advanced Research Project Agency High-Frequency Integrated Vacuum Electronics (HiFIVE) program intended for the realization of awideband(∼30%) 220-GHz traveling wave tube. The ellipti- cal cathode with homogeneous microstructure was made from 1–2-µm-size tungsten powder addedwith nanosized Scandia using the sol-gel method; it has a Current Density of up to 160 A/cm2 at 1050 ◦C. A sheet beam gun analyzer was built to test the terahertz sheet beam gun and determine the size and Current Density of a sheet electron beam produced by the impregnated scandate tungsten dispenser cathode. A sheet electron beam with an aspect ratio of 12.5 : 1 with a Current Density exceeding 375 A/cm2 has been obtained using a BVERI impregnated scandate dispenser cathode without magnetic compression; further magnetic field compression would give the final Current Density of 750 A/cm2.
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High Current Density and long-life nanocomposite scandate dispenser cathode fabrication
IEEE Transactions on Electron Devices, 2011Co-Authors: Jinfeng Zhao, Mike Banducci, Larry R. Barnett, Diana Gamzina, Zuhair A. Munir, Na Li, Ji Li, Neville C. LuhmannAbstract:A nano-Sc2O3-added W powder for use in High Current Density thermionic cathodes has been made using a solution–gel method with the following controllable uni- form average particle sizes: ∼72, 146, 272, and 587 nm. Using these powders, nanostructured Sc2O3-added tungsten matrices with uniform nanosized tungsten grains and ho- mogenous pore distribution were obtained. Nanocomposite Sc2O3-added W impregnated cathodes have been prepared from these powders and have shown excellent emission prop- erties. For example, space-charge-limited Current densities of 40±1A · cm−2 at 850 ◦C and 170±5A · cm−2 at 1050 ◦C have been obtained using a 300-nm Sc2O3-added (4.77 wt.%) W powder. Life testing is ongoing with 50±2.5 A · cm−2 Current Density emission demonstrated at 1050 ◦C after 10 680 h.
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Development of High Current-Density Cathodes With Scandia-Doped Tungsten Powders
IEEE Transactions on Electron Devices, 2007Co-Authors: Yiman Wang, Jinshu Wang, Ke Zhang, Ji LiAbstract:The development of High Current-Density cathodes employing scandia-doped tungsten powders is reviewed in this paper. A matrix with a submicrometer microstructure characterized by uniformly distributed nanometer particles of scandia is believed to play a dominant role in the improved emission capability of these cathodes. Space-charge-limited Current densities of over 30 A/cm2 at 850 degCb have been repeatedly obtained for many runs of cathodes fabricated from the different batches of scandia-doped tungsten powders. A lifetime of over 10000 h at 950-degCb 2-A/cm2 dc loading in a test diode has been achieved. Periodic High Current-Density pulse testing was also carried out during the test. The performance for both the dc and pulsed Current densities remained stable. When tested at Stanford Linear Accelerator Center in a cathode life test vehicle with a Pierce gun configuration, the cathode operated for 500 h at 1170 degC b, with a pulsed loading of 100 A/cm2 and with less than 5% degradation in Current Density. The outstanding performance of these cathodes is attributed to a surface multilayer of Ba-Sc-O of about 100-nm thickness that uniformly covers the W grains with nanometer-size particles distributed on the growth steps. The layer is formed after proper activation by diffusion of free or ionic Sc together with Ba and O from the interior of the cathode to its surface. This Highly mobile, free, or ionic Sc is liberated from constituents produced during impregnation and activation by reactions between the matrix materials and impregnants
R Wei - One of the best experts on this subject based on the ideXlab platform.
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low energy High Current Density ion implantation of materials at elevated temperatures for tribological applications
Surface & Coatings Technology, 1996Co-Authors: R WeiAbstract:Low energy, High Current Density ion implantation at elevated temperatures has been shown to improve significantly the tribological properties of various materials. This paper summarizes the results published previously in this research area and presents some new results. Comparisons of this technique are made with ion nitriding and High energy ion implantation conducted under similar conditions (treatment temperature, treatment time and so on) on austenitic stainless steel and tool steel materials. The microstructural analyses and tribological evaluations presented here show that all three techniques generate almost identical microstructures on each metal studied, but low energy ion implantation produces treated layers with Higher nitrogen concentrations and deeper diffusion, leading to Higher wear resistance. A physical model is proposed to explore the mechanisms for these advantageous phenomena. The analysis suggests that a High Current Density is the primary mechanism responsible for the formation of deep nitrogen-containing layers. The ion energy is of secondary importance, as long as it is sufficiently High to overcome certain surface barrier potentials, to allow the removal of native oxide layers, to prevent surface oxidation and to allow the build-up of a High concentration of atomic nitrogen on the top of the treated surface to facilitate subsequent fast diffusion. Some applications and limitations of this technique are also addressed. It seems evident that low energy implantation (slightly Higher than for ion nitriding, but much lower than for High energy ion implantation) at High Current densities (much Higher than those used in both ion nitriding and High energy implantation) generates superior nitrogen-containing layers on many materials, and hence the superior tribological performance compared to the other two techniques.