Download or read book Ultra fast High Temperature Microwave Processing of Silicon Carbide and Gallium Nitride written by Siddarth G. Sundaresan and published by . This book was released on 2007 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A novel solid-state microwave annealing technique is developed in this work for post-implantation annealing of SiC and GaN, and for the controlled growth of SiC nanowires. This technique is capable of heating SiC samples to temperatures in excess of 2100 °C, at ultra-fast temperature ramping rates> 600 °C/s. Microwave annealing of ion-implantation doped (both p-type and n-type) hexagonal SiC was performed in an uncontrolled (air) ambient, as well as a controlled 100% atmosphere of nitrogen, with or without a protective graphite cap. Microwave annealing was performed in the temperature range of 1500 °C -- 2120 °C, for durations of 5 s -- 60 s. Uncontrolled ambient microwave annealing of SiC at temperatures> 1700 °C resulted in a significant oxidation of the SiC surface, leading to a loss of the implanted layer. Annealing in a 100% nitrogen atmosphere eliminated the oxidation problem. For microwave annealing at temperatures [greater than or equal to] 1800 °C, significant SiC sublimation was observed, even for 15 s annealing. Microwave annealing with a photoresist-converted graphite cap solved this surface sublimation problem for annealing temperatures up to 2100 °C. For the P+ and Al+ -implanted SiC, sheet resistances as low as 14 [Omega]/ and 1.9 k[Omega]/ and majority carrier mobilities as high as 100 cm2/Vs and 8.3 cm2/Vs, respectively, were obtained. For the Al+ -implanted SiC, sheet resistances as low as 1.9 k[Omega]/ and hole mobilties as high as 8.3 cm2/Vs were obtained. These values constitute the best ever reported electrical characteristics for ion-implanted SiC. Microwave annealing at temperatures> 1800 °C not only removed the implantation-induced lattice damage but also the defects introduced during crystal growth. Microwave annealing of in-situ as well as ion-implantation acceptor doped GaN was performed in the temperature range of 1200 °C -- 1600 °C, for a duration of 5 s, using different protective caps (AlN, MgO, graphite) for protecting GaN surfaces during annealing. Pulsed-laser deposited AlN was found to protect the GaN surface effectively, for microwave annealing at temperatures as high as 1500 °C. The RMS surface roughness (0.6 nm) of the GaN sample annealed at 1500 °C with an AlN cap is similar to the value (0.3 nm) measured on the as-grown sample with a decrease in the compensating deep donor concentration. Cubic 3C-SiC nanowires were grown by a novel Fe, Ni, Pd, and Pt metal catalystassisted sublimation-sandwich (SS) method. The nanowire growth was performed in a nitrogen atmosphere, in the temperature range of 1650 °C to 1750 °C for 40 s durations. The nanowires grow by the vapor-liquid-solid (VLS) mechanism facilitated by metal catalyst islands. The nanowires are 10 [micrometer] to 30 [micrometer] long with about 52% of them having diameters in the range of 15 nm -- 150 nm, whereas 14% of the nanowires had diameters in excess of 300 nm"--Abstract.

Download or read book Ultra Fast Microwave Annealing of Silicon Carbide and Gallium Nitride written by V Rao Mulpuri and published by LAP Lambert Academic Publishing. This book was released on 2015-06-02 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel solid-state microwave annealing technique is developed for post-implantation annealing of silicon carbide (SiC) and Gallium Nitride (GaN), and for the controlled growth of SiC nanowires. This technique is capable of heating SiC samples to temperatures in excess of 2100 C, at ultra-fast temperature ramping rates > 600 C/s. For phosphorus and aluminum implanted SiC, sheet resistances as low as 14 /sq and 1.9 k /sq and majority carrier mobilities as high as 100 cm2/Vs and 8.3 cm2/Vs, respectively, are obtained. For the Al+ -implanted SiC, hole mobilties as high as 8.3 cm2/Vs is obtained. These values constitute the best ever reported electrical characteristics for high-dose ion-implanted SiC. Microwave annealing of in-situ as well as ion-implantation acceptor doped GaN was performed in the temperature range of 1200 C - 1600 C, for a duration of 5 s, using different protective caps (AlN, MgO, graphite). A patented, metal catalyst assisted sublimation sandwich method is invented for the growth of microwave-heating assisted cubic 3C-SiC nanowires."

Download or read book Gallium Nitride and Silicon Carbide Power Technologies 8 written by M. Dudley and published by The Electrochemical Society. This book was released on 2018-09-21 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Porous Silicon Carbide and Gallium Nitride written by Randall M. Feenstra and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porous Silicon Carbide and Gallium Nitride: Epitaxy, Catalysis, and Biotechnology Applications presents the state-of-the-art in knowledge and applications of porous semiconductor materials having a wide band gap. This comprehensive reference begins with an overview of porous wide-band-gap technology, and describes the underlying scientific basis for each application area. Additional chapters cover preparation, characterization, and topography; processing porous SiC; medical applications; magnetic ion behavior, and many more

Download or read book Microwave Processing of Silicon Carbide CRADA Final Report written by and published by . This book was released on 1998 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Systems, Inc. (LMES) and Dow Chemical Company was initiated on May 3, 1993. (Lockheed Martin Energy Research Inc. (LMER) replaced LMES). The completion date for the Agreement was December 1996. The purpose of this project is to develop microwave processing techniques to produce superior silicon carbide. Sintered silicon carbide is an attractive material for use in high-stress, high-temperature, high-wear, or highly corrosive applications. However, use in these applications has been hampered by a lack of consistency in strength, density, and other physical properties. It is proposed that the enhanced sintering that has been achieved using microwaves in oxide and halide systems be applied to the sintering of these materials to produce a more highly controlled density and microstructure. This will, in turn, increase the strength and Weibull modulus of the sintered body. The use of microwave energy to anneal for a moderate temperature (1,400--1,600 C) anneal in a high vacuum (

Download or read book Microwave Processing of Materials written by and published by . This book was released on 1992 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microwave Processing of Silicon Carbide written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gallium Nitride Processing for Electronics Sensors and Spintronics written by Stephen J. Pearton and published by Springer Science & Business Media. This book was released on 2006-07-06 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor spintronics is expected to lead to a new generation of transistors, lasers and integrated magnetic sensors that can be used to create ultra-low power, high speed memory, logic and photonic devices. Useful spintronic devices will need materials with practical magnetic ordering temperatures and current research points to gallium and aluminium nitride magnetic superconductors as having great potential. This book details current research into the properties of III-nitride semiconductors and their usefulness in novel devices such as spin-polarized light emitters, spin field effect transistors, integrated sensors and high temperature electronics. Written by three leading researchers in nitride semiconductors, the book provides an excellent introduction to gallium nitride technology and will be of interest to all reseachers and industrial practitioners wishing to keep up to date with developments that may lead to the next generation of transistors, lasers and integrated magnetic sensors.

Download or read book Microwave Processing of Silicon Nitride Bonded Silicon Carbide Refractory Material written by Ahmed Yussef Abd-Allah Mosbah and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rapid Silicon Carbide Crystal Growth with High Power Laser Heating Method written by Haonan Zhou and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research presents an ultra-fast procedure to grow silicon carbide crystal with the size up to 50 m from Nano size powder. By using high power laser beam in vacuum environment, the silicon carbide nanometer powder will be heated to an extremely high temperature in few seconds. The laser beam will be held for several minutes and then cooling down slowly. The silicon carbide powder will grow to micro size crystal in minutes. This research examines the silicon carbide structure before and after the laser beam heating. The composition of the final product is determined by SEM, EDS and XRD. The type of main product and the growing direction is characterized and the growing process presents in two steps. For comparison, different percentages of power and heating methods applied for laser beam.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 906 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Microwave Processing of Silicon Nitride Components for Advanced Heat Engine Applications Microwave Annealing of Silicon Nitride with High Additive Contents written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Microwave Processing of Silicon Nitride Components for Advanced Heat Engine Applications Microwave Annealing of Silicon Nitride with High Additive Contents CRADA Final Report for CRADA Number ORNL90 0035 written by and published by . This book was released on 1994 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The initial work on microwave annealing of dense silicon nitride showed enhanced grain growth and improved creep resistance for materials annealed at temperatures of 1,200--1500 C. In those tests, the anneal times were on the order of 10--20 h to achieve the observed changes. To further study the effectiveness of microwave annealing, a Cooperative Research and Development Agreement (CRADA) was started in the area of microwave processing of silicon nitride with Garrett Ceramic Components/Allied-Signal (GCC/AS). The original plan was for ORNL to microwave anneal specimens of dense silicon nitride with high additive contents (> 5%) provided by GCC/AS at various times and temperatures. There were to be three sample types and 3--4 annealing conditions for a total of 9--12 annealing runs. The materials would then be characterized by both ORNL and GCC/AS to determine any changes in the properties. The objectives were: (1) to determine the effects of microwave crystallization on mechanical properties, and (2) to compare the effectiveness of microwave versus conventional heating. The mechanical properties examined that were fracture toughness, flexural strength and high temperature stress rupture. Delays, organizational changes, and other commercialization priorities resulted in a termination of this CRADA. This report contains a summary of results from one silicon nitride composition.

Download or read book Advances in Induction and Microwave Heating of Mineral and Organic Materials written by Stanisław Grundas and published by IntechOpen. This book was released on 2011-02-14 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book offers comprehensive coverage of the broad range of scientific knowledge in the fields of advances in induction and microwave heating of mineral and organic materials. Beginning with industry application in many areas of practical application to mineral materials and ending with raw materials of agriculture origin the authors, specialists in different scientific area, present their results in the two sections: Section 1-Induction and Microwave Heating of Mineral Materials, and Section 2-Microwave Heating of Organic Materials.

Download or read book Studies on the Scale up of the Microwave assisted Nitridation and Sintering of Reaction bonded Silicon Nitride written by and published by . This book was released on 1996 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies using laboratory test samples have shown that microwave heating produces sintered reaction-bonded silicon nitride materials with improved properties. The final challenge for processing this material by microwave heating is the development of a technology for processing larger batch-size quantities of these materials. Initial microwave scale-up experiments were performed using powder compacts of a bucket tappet geometry. In experiments using microwave-transparent boron nitride sample crucibles, temperature gradients within some crucibles led to larger variations in the sample densities than were obtained with the conventionally processed samples. The use of a microwave-suscepter type crucible made of silicon carbide and boron nitride resulted in an improved temperature uniformity and in density variations comparable to those obtained for the control groups.

Download or read book Non destructive X ray Characterization of Wide bandgap Semiconductor Materials and Device Structures written by Nadeemullah A. Mahadik and published by . This book was released on 2008 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work non-destructive x-ray characterization techniques have been used to study undoped and intentionally doped bulk and epitaxial layers, and device structures of wide bandgap semiconductor materials, GaN and SiC. Novel non-destructive x-ray characterization methods were developed to evaluate the uniformity of strain in AlGaN/GaN device structures across the wafer and the results were correlated with device electrical characteristics. In-situ bias induced strain measurements were also carried out for the first time on the AlGaN/GaN Schottky diodes to estimate change in piezoelectric polarization charge at the heterojunction interface with the gate bias voltage. A variety of high resolution x-ray measurements were performed on freestanding Gallium Nitride (GaN) films grown by three different laboratories using hydride phase vapor epitaxy (HVPE) technique. The lattice parameters of the quasi-bulk films were obtained using high-resolution x-ray diffraction spectra. The crystalline quality of the films was determined by measuring the x-ray rocking curves and by ^71 Ga nuclear magnetic resonance (NMR) technique. The anisotropic in-plane strain was determined using a novel grazing incidence x-ray diffraction technique (GID) and conventional x-ray diffraction measurements. Based on these measurements the best free standing films have surface strain anisotropy of 4.0791 x 10^-3 up to a depth of 0.3 [Mu]m and the dislocation density is in the range of 10^5-10^7 /cm^2. High resolution x-ray topography (HRXT) measurements were also performed on the freestanding GaN films. Complete mapping of defects for the entire surface of the GaN films was obtained in a non-destructive way. From these measurements, the lateral dimensions of crystallites and cavities in the films are in the range, 200-500 nm, and 0.5-400 [Mu]m, respectively. The GaN films were found to be warped with a radius of curvature of about 0.5 m. The warpage is attributed to thermal mismatch between GaN and the sapphire substrate during growth. The characteristics of freestanding GaN films measured in this work are detrimental to the fabrication of high-speed devices such as high electron mobility transistors (HEMT) because their performance is highly dependent on the surface and interface quality. High resolution x-ray measurements were also performed on Al+ ion-implanted 4H-Silicon Carbide (SiC) epitaxial layers, before and after 30s ultra-fast microwave annealing in the temperature range 1750-1900 °C, to examine the crystalline quality of the material. Based on the FWHM values of the rocking curves, an improvement in the crystalline quality of the microwave annealed samples was observed compared to the conventional furnace annealed sample. The sample annealed at 1900 °C showed the best rocking curve FWHM of 9 " 2 arcsecs, which not only confirmed annihilation of the defects introduced during the Al+ ion-implantation process, but also an improvement in crystalline quality over the as-grown virgin 4H-SiC sample that had a rocking curve FWHM of 18.7 " 2 arcsecs. The theoretical and measured rocking curve FWHM values were obtained and correlated with the depth dependent microwave absorption in the SiC epilayer. These results are very significant for optimizing the annealing parameters to achieve the highest possible implant activation, carrier mobility and crystal quality. Magnesium ion-implantation doped GaN films were also characterized using x-ray diffraction measurements after microwave annealing in the temperature range of 1300 °C - 1500 °C for 5 - 15 s. The FWHM values of the in-situ Mg-doped samples did not change with the microwave annealing for 5 s anneals. The electrical measurements on these samples also showed poor electrical activation of the Mg-implant in the GaN films. These results may be due to the presence of a high concentration of implant generated defects still remaining in the material, even after high temperature annealing for 5 s. From the FWHM values, the 15 s annealing showed an improvement in the crystalline quality of the GaN samples. Also the x-ray diffraction measurements show activation of the Mg implant. Electrical conductivity was observed in these samples, which is due to significant improvement in the crystalline quality and sufficient activation of the Mg implant. In this work, x-ray measurements were also performed on AlGaN/GaN device structures to study the effect of localized strain on the transport measurements across the wafer. The map of in-plane strain of the AlGaN/GaN HEMT wafer showed a one-to-one correspondence with the variation in electrical resistivity. The in-plane strain variation is in the range of 2.295x10^-4 - 3.539x10^-4 resulting in a sheet resistance variation of 345 - 411. The in-situ high resolution x-ray diffraction measurements, performed on the AlGaN/GaN device structures under variable bias conditions, showed in-plane tensile strain for forward bias conditions, and compressive strain for reverse bias. A linear variation in the strain was observed with the bias voltage, which results in a change in the piezoelectric charge at the AlGaN/GaN interface with bias. This variation needs to be considered for the correct modeling of the device transport characteristics.

Download or read book Gallium Nitride Processing for High Power Microwave Devices written by Luke Farrant and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: