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Electrical Characterization Of Process And Radiation Induced Defects In 4h Sic
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Book Synopsis Electrical Characterization of Process- and Radiation-induced Defects in 4H-SiC by : Ezekiel Omotoso
Download or read book Electrical Characterization of Process- and Radiation-induced Defects in 4H-SiC written by Ezekiel Omotoso and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Devices for operation in aerospace, manufacturing industries, defence and radiation-harsh environments need to be manufactured from materials that are resistant to the frequent damage caused by irradiation and high-temperature environments. Silicon carbide (SiC) is a wide-bandgap semiconductor material that promises to provide solutions to these problems based on its capability to operate under extreme conditions of temperature and radiation. These conditions introduce defects in the materials. Such defects play an important role in determining the properties of devices, albeit beneficial or detrimental. Therefore it is very important to characterize the defects present in as-grown material as well as defects introduced during processing and irradiation. In this research, resistive evaporation (RE) as well as electron-beam deposition was employed for the fabrication of ohmic and Schottky barrier contacts on nitrogen-doped, n-type 4H-SiC substrate. The quality of the Schottky barrier diodes (SBDs) deposited was confirmed by current-voltage (I-V) and capacitance-voltage (C-V) measurements. Deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS were successfully used to characterize the electrically active defects present in the 4H-SiC SBDs before and after bombarding them with high-energy electrons and alpha-particles as well as after exposing the sample to electron beam deposition conditions. I-V and C-V measurements showed that the SBDs deposited by RE were of good quality with an ideality factor close to unity, a low series resistance and low reverse leakage current. After irradiation, the electrical properties deviated significantly based on the irradiation types and fluences. Thermionic emission dominated at high temperatures close to room temperature, while other current transport mechanisms became dominant at lower temperatures. The ideality factor increased and Schottky barrier heights decreased with decreasing temperature.
Book Synopsis Electrical Characterization of Process-induced Defects in 4H-SiC by : Shandirai Malven Tunhuma
Download or read book Electrical Characterization of Process-induced Defects in 4H-SiC written by Shandirai Malven Tunhuma and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon carbide has become an important material in the implementation of next generation photonics. It harbors the silicon vacancy (VSi) which can be transformed to a carbon antisite-vacancy pair (CSiVC) defect through thermal treatment. This defect has quantum functionality and can be used as a single photon source at room temperature. Using defect engineering, this technology is set to surpass advances made in other similar systems because it is being developed on existing standard industrial practices, fabrication protocols and mechanisms. These include techniques such as irradiation, annealing and ion implantation. The motivation of this work was to establish sound device fabrication protocols to be used in the device implementation. In this thesis DLTS and Laplace DLTS have been used to characterize deep level defects induced by various processes in 4H-SiC. Schottky barrier diodes were used to create the space charge region required to probe the defect characteristics using capacitance DLTS. From the DLTS and Laplace DLTS the activation energies of the defects were accurately deduced and the apparent capture cross section was calculated. The defect concentration was also quanti ed in the form of depth pro les plotted from the metal-semiconductor interface of the Schottky barrier diodes into the bandgap of the semiconductor. SEM, AFM and XRD were used to probe the changes in surface morphology and composition accompanying the processing steps whilst Raman spectroscopy was used to probe the nature of induced defects. Sputter deposition of tungsten on 4H-SiC was successfully used to induce the E0:69 which is the VSi. The identity of VSi was con rmed by thermal treatment and it annealed beyond detection at 600 C as expected. A previously unreported defect, the E0:29 was also observed after sputtering and was attributed to the heavy metal and gas ion residue from the deposition process. In order to transform the VSi into CSiVC, W/4H-SiC diodes were annealed up to 1100 C. This resulted in the formation of defects which were attributed to the interdi usion of silicides and carbides formed at the W/4H-SiC interface, as detected by XRD, migrating into the SiC. This was an unfavourable outcome for photonics applications where purity of the semiconductor is a major concern. As an alternative solution, the VSi was induced in 4H-SiC using 167 MeV, Xe26+ swift heavy ions. Xe is a noble gas therefore it would not react with the semiconductor. The structure and integrity of the lattice structure was conserved after irradiation as deduced from confocal Raman microscopy. The depth and concentration of the defects as observed in confocal Raman was consistent with SRIM simulations. AFM showed that the radiation introduced elongated protrusions on the surface of the semiconductor. The observations show that the silicon vacancy can be induced in 4H-SiC by standard industrial practices such as sputter deposition or ion irradiation.
Book Synopsis Electrical Characterization of Radiation Induced Defects in 3C-SiC by : Matthew John Cabral
Download or read book Electrical Characterization of Radiation Induced Defects in 3C-SiC written by Matthew John Cabral and published by . This book was released on 2013 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Study of the Effects of Neutron Irradiation and Low Temperature Annealing on the Electrical Properties of 4H Silicon Carbide by : Stephen E. Stone
Download or read book A Study of the Effects of Neutron Irradiation and Low Temperature Annealing on the Electrical Properties of 4H Silicon Carbide written by Stephen E. Stone and published by . This book was released on 2008 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Recent advancements in growth technology have made silicon carbide (SiC) a feasible option for use as a semiconductor material in electronic devices. Its mechanical and electrical properties make it a desirable choice for high-power high-frequency devices as well as for use in harsh environments. It is therefore necessary to understand the response of SiC's electrical properties to radiation induced damage. The effects of neutron irradiation on the electrical properties of highly doped 4H SiC were studied. Bulk 4H SiC with a low resistivity of ~0.018[Omega]-cm was utilized in this work. The material was fabricated into standard Hall bars for characterization of the material's resistivity, free carrier concentration and electron Hall mobility as a function of 1 MeV neutron equivalent fluence. Also investigated were the post irradiation effects of low temperature annealing (175C) on the same properties. It was found that the material's resistivity doubled as fluences of 2.7x10^16cm-2 were reached and did not incur any significant recovery as a function of annealing. It was also found that this material suffers from a carrier removal rate of ~48.5 n cm-1 when related linearly to 1 MeV fluence. This reduction in free carrier concentration was attributed to defects locally deactivating donor sites in the material. These defects were unstable at low temperatures as the carrier concentration recovered completely as a result of the annealing process. The Hall mobility was also found to degrade with fluence. At room temperature this degradation is a combination of an increase in mobility due to neutralized donors and a decrease due to increased scattering from electrically inactive defects. These electrically inactive defects were found to be stable at 175C and were the major contributor to the stable long term increase in resistivity.
Book Synopsis Electrical and Optical Characterization of Intrinsic and Ion- Implantation Induced Defects in 6H- And 4H-SiC by : Michael B. Scott
Download or read book Electrical and Optical Characterization of Intrinsic and Ion- Implantation Induced Defects in 6H- And 4H-SiC written by Michael B. Scott and published by . This book was released on 1999-11-01 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep level transient spectroscopy (DLTS), Hall effect, and cathodolummescence (CL) measurements are used to characterize the intrinsic and ion-implantation induced defects in high-temperature (475 and 500 deg C) ion- implanted epitaxial n-type 6H- and 4H-SiC, ion-implanted with Cr, Mg, Ar, N, and P atoms. Comparison of room-temperature and high-temperature ion-implanted 6H- SiC:Mg and :Cr indicate the significance of high-temperature ion implantation on the activation of the ion-implanted atoms and damage-recovery of the crystalline lattice. The effects of high-temperature annealing on both damage-recovery and implanted ion activation are detected and analyzed, from 1200 to 1800 degrees C. Trap parameters 0 both damage-related and species-related defects are determined by curve-fitting of DLTS rate window plots, including the identification of a 615 meV silicon-vacancy-substitutional-nitrogen defect. Double-correlated DLTS measurements indicate a one-dimensional distribution of various defects along the implantation axis and slight surface diffusion of ion-implanted magnesium during high-temperature annealing. Current-voltage-temperature measurements of 6H-SiC:Mg :Cr indicate the effect of annealing temperature and ion species on the concentration of near midgap defects. Optimum anneal temperatures are determined for activation of ion-implanted nitrogen and phosphorus. CL measurements indicate the formation of deep radiative centers in 500 degrees C ion-implanted 4H-SiC:P and :N. CL measurements also indicate the presence of a 130 meV higher energy level conduction band minimum.
Book Synopsis Characterization of Process and Radiation Induced Defects in Si and Ge Using Conventional Deep Level Transient Spectroscopy (DLTS) and Laplace-DLTS by : Cloud Nyamhere
Download or read book Characterization of Process and Radiation Induced Defects in Si and Ge Using Conventional Deep Level Transient Spectroscopy (DLTS) and Laplace-DLTS written by Cloud Nyamhere and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Defects in semiconductors are crucial to device operation, as they can either be beneficial or detrimental to the device operation depending on the application. For efficient devices it is important to characterize the defects in semiconductors so that those defects that are bad are eliminated and those that are useful can be controllably introduced. In this thesis, deep level transient spectroscopy (DLTS) and high-resolution Laplace-DLTS (LDLTS) have been used to characterize deep level defects introduced by energetic particles (electrons or Ar ions) and during metallization using electron beam deposition on silicon and germanium. Schottky diodes were used to form the space-charge region required in DLTS and LDLTS measurements. From the DLTS and LDLTS measurements the activation enthalpy required to ionize a trap, ET, and defect carrier capture cross-section?? were deduced. LDLTS proved particularly useful since it could separate deep levels with closely spaced energy levels (the limit being defects with emission rates separated by a factor greater than 2), which was not possible by conventional DLTS. The majority carrier traps in gallium-, boron- and phosphorus-doped silicon introduced after MeV electron irradiation and during electron beam deposition have been characterized, and several defects such as the divacancy, A-center and E-center and other complex defects were observed after the two processes. Annealing studies have shown that all deep levels are removed in silicon after annealing between 500ʻC-600ʻC. Both electron and hole traps introduced in n-type germanium by electron irradiation, Ar sputtering and after electron beam deposition have been characterized using DLTS and LDLTS. The E-center is the most common defect introduced in germanium after MeV electron irradiation and during electron beam deposition. Annealing shows that defects in germanium were removed by low thermal budget of between 350ʻC - 400ʻC and it has been deduced that the E-center (V-Sb) in germanium anneals by diffusion. The identification of some of the defects was achieved by using defect properties such as defect signature, introduction rates, annealing behavior and annealing mechanisms, and then comparing these properties to theoretical defect models and results from other techniques.
Book Synopsis Electrical Characterization of Intrinsic and Induced Deep Level Defects in Hexagonal SiC by : James D. Scofield
Download or read book Electrical Characterization of Intrinsic and Induced Deep Level Defects in Hexagonal SiC written by James D. Scofield and published by . This book was released on 1996-12-01 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep level defects in hexagonal SiC were studied using digital deep level transient spectroscopy (DLTS) methods over the temperature range of 100 to 800 deg K. New centers were found in bulk and epitaxial 6H-SiC with ionization energies between 0.38 to 1.3 eV, and levels from 0.2 to 0.856 eV were identified in 4H-SiC epitaxy. Direct correlation between inequivalent lattice sites was identified for energetic pairs associated with both vanadium and ion implanted Mg impurities. Nonradioative carrier capture mechanisms were studied and deep level trapping was found to proceed via lattice relaxation multi-phonon emission, indicating efficient electronic lattice coupling in the wide bandgap material. Junction transport characteristics of 4H-SiC p+/n bipolar devices were observed to be dominated by deep level defects in the epitaxial layers. Significant tunneling conduction in both forward and reverse bias conditions was directly correlated to deep level centers in these devices.
Book Synopsis Silicon Carbide Microsystems for Harsh Environments by : Muthu Wijesundara
Download or read book Silicon Carbide Microsystems for Harsh Environments written by Muthu Wijesundara and published by Springer Science & Business Media. This book was released on 2011-05-17 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon Carbide Microsystems for Harsh Environments reviews state-of-the-art Silicon Carbide (SiC) technologies that, when combined, create microsystems capable of surviving in harsh environments, technological readiness of the system components, key issues when integrating these components into systems, and other hurdles in harsh environment operation. The authors use the SiC technology platform suite the model platform for developing harsh environment microsystems and then detail the current status of the specific individual technologies (electronics, MEMS, packaging). Additionally, methods towards system level integration of components and key challenges are evaluated and discussed based on the current state of SiC materials processing and device technology. Issues such as temperature mismatch, process compatibility and temperature stability of individual components and how these issues manifest when building the system receive thorough investigation. The material covered not only reviews the state-of-the-art MEMS devices, provides a framework for the joining of electronics and MEMS along with packaging into usable harsh-environment-ready sensor modules.
Book Synopsis Electrical Characterisation of Plasma Processing Induced Defects in Silicon by : Prakash Narayen Kripalini Deenapanray
Download or read book Electrical Characterisation of Plasma Processing Induced Defects in Silicon written by Prakash Narayen Kripalini Deenapanray and published by . This book was released on 1997 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Radiation Effects in Advanced Semiconductor Materials and Devices by : C. Claeys
Download or read book Radiation Effects in Advanced Semiconductor Materials and Devices written by C. Claeys and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This wide-ranging book summarizes the current knowledge of radiation defects in semiconductors, outlining the shortcomings of present experimental and modelling techniques and giving an outlook on future developments. It also provides information on the application of sensors in nuclear power plants.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evolution of Radiation Induced Defects in SiC by : Hao Jiang
Download or read book Evolution of Radiation Induced Defects in SiC written by Hao Jiang and published by . This book was released on 2017 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of various excellent properties, SiC has been proposed for many applications in nuclear reactors including cladding layers in fuel rod, fission products container in TRISO fuel, and first wall/blanket in magnetic controlled fusion reactors. Upon exposure to high energy radiation environments, point defects and defect clusters are generated in materials in amounts significantly exceeding their equilibrium concentrations. The accumulation of defects can lead to undesired consequences such as crystalline-to-amorphous transformation1, swelling, and embrittlement, and these phenomena can adversely affect the lifetime of SiC based components in nuclear reactors. It is of great importance to understand the accumulation process of these defects in order to estimate change in properties of this material and to design components with superior ability to withstand radiation damages. Defect clusters are widely in SiC irradiated at the operation temperatures of various reactors. These clusters are believed to cause more than half of the overall swelling of irradiated SiC and can potentially lead to lowered thermal conductivity and mechanical strength. It is critical to understand the formation and growth of these clusters. Diffusion of these clusters is one importance piece to determine the growth rate of clusters; however it is unclear so far due to the challenges in simulating rare events. Using a combination of kinetic Activation Relaxation Technique with empirical potential and ab initio based climbing image nudged elastic band method, I performed an extensive search of the migration paths of the most stable carbon tri-interstitial cluster in SiC. This research reveals paths with the lowest energy barriers to migration, rotation, and dissociation of the most stable cluster. Based on these energy barriers, I concluded defect clusters are thermally immobile at temperatures lower than 1500 K and can dissociate into smaller clusters and single interstitials at temperatures beyond that. Even though clusters cannot diffuse by thermal vibrations, we found they can migrate at room temperature under the influence of electron radiation. This is the first direct observation of radiation-induced diffusion of defect clusters in bulk materials. We show that the underlying mechanism of this athermal diffusion is elastic collision between incoming electrons and cluster atoms. Our findings suggest that defect clusters may be mobile under certain irradiation conditions, changing current understanding of cluster annealing process in irradiated SiC. With the knowledge of cluster diffusion in SiC demonstrated in this thesis, we now become able to predict cluster evolution in SiC with good agreement with experimental measurements. This ability can enable us to estimate changes in many properties of irradiated SiC relevant for its applications in reactors. Internal interfaces such as grain boundaries can behave as sinks to radiation induced defects. The ability of GBs to absorb, transport, and annihilate radiation-induced defects (sink strength) is important to understand radiation response of polycrystalline materials and to better design interfaces for improved resistance to radiation damage. Nowadays, it is established GBs' sink strength is not a static property but rather evolves with many factors, including radiation environments, grain size, and GB microstructure. In this thesis, I investigated the response of small-angle tilt and twist GBs to point defects fluxes in SiC. First of all, I found the pipe diffusion of interstitials in tilt GBs is slower than bulk diffusion. This is because the increased interatomic distance at dislocation cores raises the migration barrier of interstitial dumbbells. Furthermore, I show that both the annihilation of interstitials at jogs and jog nucleation from clusters are diffusion-controlled and can occur under off-stoichiometric interstitial fluxes. Finally, a dislocation line model is developed to predict the role of tilt GBs in annihilating radiation damage. The model predicts the role of tilt GBs in annihilating defects depends on the rate of defects segregation to and diffusion along tilt GBs. Tilt GBs mainly serve as diffusion channel for defects to reach other sinks when defect diffusivity is high at boundaries. When defect diffusivity is low, most of the defects segregated to tilt GBs are annihilated by dislocation climb. Up-to-date, the response of twist GBs under irradiation has been rarely reported in literature and is still unclear. It is important to develop atom scale insight on this question in order to predict twist GBs' sink strength for a better understanding of radiation response of polycrystalline materials. By using a combination of molecular dynamics and grand canonical Monte Carlo, here I demonstrate the defect kinetics in {001} and {111} twist GBs and the microstructural evolution of these GBs under defect fluxes in SiC. I found due to the deep potential well for interstitials at dislocation intersections within the interface, the mobility of defects on dislocation grid is retard and this leads to defect accumulation at GBs for many cases. Furthermore, I conclude both types of twist GBs have to form mixed dislocations with edge component in order to absorb accumulated interstitials at the interface. The formation of mixed dislocation is either by interstitial loop nucleation or by dislocation reactions at the interface. The continuous formation and climb of these mixed dislocations make twist GBs unsaturatable sinks to radiation induced defects.
Book Synopsis Silicon Carbide and Related Materials 1995, Proceedings of the Sixth INT Conference, Kyoto, Japan, 18-21 September 1995 by : Shin-ichi Nakashima
Download or read book Silicon Carbide and Related Materials 1995, Proceedings of the Sixth INT Conference, Kyoto, Japan, 18-21 September 1995 written by Shin-ichi Nakashima and published by CRC Press. This book was released on 1996 with total page 1158 pages. Available in PDF, EPUB and Kindle. Book excerpt: The special advantages of silicon carbide and related materials such as III-V nitrides in applications in hostile environments and for blue-light-emitting diodes continue to stimulate research and development activity. The International Conference on Silicon Carbide and related Materials is now the established forum for exchanging information on advances in this subject. This volume includes both invited and contributed papers covering the whole field of silicon carbide and related materials research, from the fundamental physics of these materials, through their growth, control of properties, characterization, surface and interface modification, device processing and fabrication, to simulation and modelling. Materials scientists, electronic engineers and solid state physicists who work with these materials, as well as those who are contemplating research in this expanding field, will find this a unique single source of information.
Book Synopsis The influence of process induced defects on electrical properties of silicon junctions by : Gert I. Andersson
Download or read book The influence of process induced defects on electrical properties of silicon junctions written by Gert I. Andersson and published by . This book was released on 1992 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Electrical Properties of 4H-SiC by Imaging Techniques by : John Österman
Download or read book Characterization of Electrical Properties of 4H-SiC by Imaging Techniques written by John Österman and published by . This book was released on 2004 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Silicon Carbide by : Wolfgang J. Choyke
Download or read book Silicon Carbide written by Wolfgang J. Choyke and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 911 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1997 publication of "Silicon Carbide - A Review of Fundamental Questions and Applications to Current Device Technology" edited by Choyke, et al., there has been impressive progress in both the fundamental and developmental aspects of the SiC field. So there is a growing need to update the scientific community on the important events in research and development since then. The editors have again gathered an outstanding team of the world's leading SiC researchers and design engineers to write on the most recent developments in SiC.
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
