| 1. |
- Aavikko, R., et al.
(författare)
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Clustering of vacancy defects in high-purity semi-insulating SiC
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:8, s. 085208-
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Tidskriftsartikel (refereegranskat)abstract
- Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity in both as-grown and annealed materials. Our results suggest that Si-vacancy-related complexes electrically compensate the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity. © 2007 The American Physical Society.
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| 2. |
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| 3. |
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| 4. |
- Carlsson, Patrick, 1975-, et al.
(författare)
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Electron paramagnetic resonance study on n-type electron-irradiated 3C-SiC
- 2008
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Ingår i: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY. - BRISTOL, ENGLAND : IOP PUBLISHING LTD.
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Konferensbidrag (refereegranskat)abstract
- Electron Paramagnetic Resonance (EPR) was used to study defects in n-type 3C-SiC films irradiated by 3-MeV electrons at room temperature with a dose of 2x10(18) cm(-2). After electron irradiation, two new EPR spectra with an effective spin S = 1, labeled L5 and L6, were observed. The L5 center has C-3v symmetry with g = 2.004 and a fine-structure parameter D = 436.5 x 10(-4) cm(-1). The L5 spectrum was only detected under light illumination and it could not be detected after annealing at similar to 550 C. The principal z-axis of the D tensor is parallel to the < 111 >-directions, indicating the location of spins along the Si-C bonds. Judging from the symmetry and the fact that the signal was detected under illumination in n-type material, the L5 center may be related to the divacancy in the neutral charge state. The L6 center has a C-2v-symmetry with an isotropic g-value of g=2.003 and the fine structure parameters D=547.7 x 10(-4) cm-1 and E=56.2 x 10(-4) cm(-1). The L6 center disappeared after annealing at a rather low temperature (similar to 200 degrees C), which is substantially lower than the known annealing temperatures for vacancy-related defects in 3C-SiC. This highly mobile defect may be related to carbon interstitials.
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| 5. |
- Carlsson, Patrick, 1975-, et al.
(författare)
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Intrinsic Defects in HPSI 6H-SiC : an EPR Study
- 2009
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Ingår i: Materials Science Forum, Vols. 600-603. - : Trans Tech Publications. ; , s. 381-384
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Konferensbidrag (refereegranskat)abstract
- High-purity, semi-insulating 6H-SiC substrates grown by high-temperature chemical vapor deposition were studied by electron paramagnetic resonance (EPR). The carbon vacancy (VC), the carbon vacancy-antisite pair (VCCSi) and the divacancy (VCVSi) were found to be prominent defects. The (+|0) level of VC in 6H-SiC is estimated by photoexcitation EPR (photo-EPR) to be at ~ 1.47 eV above the valence band. The thermal activation energies as determined from the temperature dependence of the resistivity, Ea~0.6-0.7 eV and ~1.0-1.2 eV, were observed for two sets of samples and were suggested to be related to acceptor levels of VC, VCCSi and VCVSi. The annealing behavior of the intrinsic defects and the stability of the SI properties were studied up to 1600°C.
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| 6. |
- Carlsson, Patrick, 1975-, et al.
(författare)
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Photo-EPR Studies on Low-Energy Electron-irradiated 4H-SiC
- 2009
-
Ingår i: Materials Science Forum, Vols. 615-617. - Materials Science Forum Vols. 615-617 : Trans Tech Publications. - 9780878493340 ; , s. 401-404
-
Konferensbidrag (refereegranskat)abstract
- Photoexcitation electron paramagnetic resonance (photo-EPR) was used to determine deep levels related to the carbon vacancy (VC) in 4H-SiC. High-purity free-standing n-type 4H-SiC epilayers with concentration of intrinsic defects (except the photo-insensitive SI1 center) below the detection limit of EPR were irradiated with low-energy (200 keV) electrons to create mainly VC and defects related to the C sublattice. The simultaneous observation of and signals, their relative intensity changes and the absence of other defects in the sample provide a more straight and reliable interpretation of the photo-EPR results. The study suggests that the (+|0) level of VC is located at ~EC–1.77 eV in agreement with previously reported results and its single and double acceptor levels may be at ~ EC–0.8 eV and ~ EC–1.0 eV, respectively.
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| 7. |
- Gali, A., et al.
(författare)
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Ab initio supercell calculations on aluminum-related defects in SiC
- 2007
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:4
-
Tidskriftsartikel (refereegranskat)abstract
- Ab initio supercell calculations of the binding energies predict complex formation between aluminum and carbon interstitials in SiC. In high-energy implanted SiC aluminum acceptor can form very stable complexes with two carbon interstitials. We also show that carbon vacancy can be attached to shallow aluminum acceptor. All of these defects produce deep levels in the band gap. The possible relation of these defects to the recently found aluminum-related deep-level transient spectroscopy centers is discussed. © 2007 The American Physical Society.
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| 8. |
- Gali, A, et al.
(författare)
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Activation of shallow boron acceptor in CB coimplanted silicon carbide : A theoretical study
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:10, s. 102108-
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio supercell calculations have been carried out to investigate the complexes of boron acceptors with carbon self-interstitials in cubic silicon carbide. Based on the calculated binding energies, the complex formation of carbon interstitials with shallow boron acceptor and boron interstitial is energetically favored in silicon carbide. These bistable boron defects possess deep, negative- U occupation levels in the band gap. The theoretical results can explain the observed activation rates in carbon-boron coimplantation experiments. © 2005 American Institute of Physics.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Gilardoni, Carmem M., et al.
(författare)
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Spin-relaxation times exceeding seconds for color centers with strong spin-orbit coupling in SiC
- 2020
-
Ingår i: New Journal of Physics. - : IOP PUBLISHING LTD. - 1367-2630. ; 22:10
-
Tidskriftsartikel (refereegranskat)abstract
- Spin-active color centers in solids show good performance for quantum technologies. Several transition-metal defects in SiC offer compatibility with telecom and semiconductor industries. However, whether their strong spin-orbit coupling degrades their spin lifetimes is not clear. We show that a combination of a crystal-field with axial symmetry and spin-orbit coupling leads to a suppression of spin-lattice and spin-spin interactions, resulting in remarkably slow spin relaxation. Our optical measurements on an ensemble of Mo impurities in SiC show a spin lifetime T-1 of 2.4 s at 2 K.
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| 15. |
- Gällström, Andreas, 1978-, et al.
(författare)
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Influence of Cooling Rate after High Temperature Annealing on Deep Levels in High-Purity Semi-Insulating 4H-SiC
- 2007
-
Ingår i: Materials Science Forum, vol. 556-557. - : Trans Tech Publications. ; , s. 371-
-
Konferensbidrag (refereegranskat)abstract
- The influence of different cooling rates on deep levels in 4H-SiC after high temperature annealing has been investigated. The samples were heated from room temperature to 2300°C, followed by a 20 minutes anneal at this temperature. Different subsequent cooling sequences down to 1100°C were used. The samples have been investigated using photoluminescence (PL) and IV characteristics. The PL intensities of the silicon vacancy (VSi) and UD-2, were found to increase with a faster cooling rate.
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| 16. |
- Hesselmeier, Erik, et al.
(författare)
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Qudit-Based Spectroscopy for Measurement and Control of Nuclear-Spin Qubits in Silicon Carbide
- 2024
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 132:9
-
Tidskriftsartikel (refereegranskat)abstract
- Nuclear spins with hyperfine coupling to single electron spins are highly valuable quantum bits. Here we probe and characterize the particularly rich nuclear-spin environment around single silicon vacancy color centers (V2) in 4H-SiC. By using the electron spin-3/2 qudit as a four level sensor, we identify several sets of Si29 and C13 nuclear spins through their hyperfine interaction. We extract the major components of their hyperfine coupling via optical detected nuclear magnetic resonance, and assign them to shells in the crystal via the density function theory simulations. We utilize the ground-state level anticrossing of the electron spin for dynamic nuclear polarization and achieve a nuclear-spin polarization of up to 98±6%. We show that this scheme can be used to detect the nuclear magnetic resonance signal of individual spins and demonstrate their coherent control. Our work provides a detailed set of parameters and first steps for future use of SiC as a multiqubit memory and quantum computing platform.
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| 17. |
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| 18. |
- Isoya, J., et al.
(författare)
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EPR Identification of Defects and Impurities in SiC : To Be Decisive
- 2009
-
Ingår i: Materials Science Forum, Vols. 600-603. - : Trans Tech Publications. ; , s. 279-284
-
Konferensbidrag (refereegranskat)abstract
- In EPR (electron paramagnetic resonance) identification of point defects, hyperfine (HF) interaction is decisive information not only for chemical identity but also for the local geometry and the electronic state. In some intrinsic defects in SiC, the wave function of the unpaired electron extends quite unevenly among major atoms comprising the defects. In such a case, the determination of the number of equivalent atoms and the chemical identity (Si or C) of those atoms even with weak HF splitting are useful to compare with HF parameters obtained theoretically. For vacancy-related defects of relatively deep levels, the sum of the spin densities on the nearest-neighbor shell is found to be 60-68%.
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| 19. |
- Isoya, J., et al.
(författare)
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EPR identification of intrinsic defects in SiC
- 2008
-
Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 245:7, s. 1298-1314
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Tidskriftsartikel (refereegranskat)abstract
- The structure determination of intrinsic defects in 4H-SiC, 6H-SiC, and 3C-SiC by means of EPR is based on measuring the angular dependence of the 29Si/13C hyperfine (HF) satellite lines, from which spin densities, sp-hybrid ratio, and p-orbital direction can be determined over major atoms comprising a defect. In most cases, not only the assignment of the variety due to the inequivalent sites (h- and k-sites in 4H-SiC) but also the identification of the defect species is accomplished through the comparison of the obtained HF parameters with those obtained from first principles calculations. Our works of identifying vacancy-related defects such as the monovacancies, divacancies, and antisite-vacancy pairs in 4H-SiC are reviewed. In addition, it is demonstrated that the observation of the central line of the TV2a center of S = 3/2 has been achieved by pulsed-ELDOR. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
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| 20. |
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| 21. |
- Ivády, Viktor, et al.
(författare)
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Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide
- 2017
-
Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 96:16
-
Tidskriftsartikel (refereegranskat)abstract
- The identification of a microscopic configuration of point defects acting as quantum bits is a key step in the advance of quantum information processing and sensing. Among the numerous candidates, silicon-vacancy related centers in silicon carbide (SiC) have shown remarkable properties owing to their particular spin-3/2 ground and excited states. Although, these centers were observed decades ago, two competing models, the isolated negatively charged silicon vacancy and the complex of negatively charged silicon vacancy and neutral carbon vacancy [Phys. Rev. Lett. 115, 247602 (2015)], are still argued as an origin. By means of high-precision first-principles calculations and high-resolution electron spin resonance measurements, we here unambiguously identify the Si-vacancy related qubits in hexagonal SiC as isolated negatively charged silicon vacancies. Moreover, we identify the Si-vacancy qubit configurations that provide room-temperature optical readout.
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| 22. |
- Janzén, Erik, 1954-, et al.
(författare)
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Defects in SiC
- 2004
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Janzén, Erik, 1954-, et al.
(författare)
-
Defects in SiC
- 2008
-
Ingår i: Defects in Microelectronic Materials and Devices. - : Taylor and Francis LLC. ; , s. 770-
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Uncover the Defects that Compromise Performance and Reliability As microelectronics features and devices become smaller and more complex, it is critical that engineers and technologists completely understand how components can be damaged during the increasingly complicated fabrication processes required to produce them.A comprehensive survey of defects that occur in silicon-based metal-oxide semiconductor field-effect transistor (MOSFET) technologies, this book also discusses flaws in linear bipolar technologies, silicon carbide-based devices, and gallium arsenide materials and devices. These defects can profoundly affect the yield, performance, long-term reliability, and radiation response of microelectronic devices and integrated circuits (ICs). Organizing the material to build understanding of the problems and provide a quick reference for scientists, engineers and technologists, this text reviews yield- and performance-limiting defects and impurities in the device silicon layer, in the gate insulator, and/or at the critical Si/SiO2 interface. It then examines defects that impact production yield and long-term reliability, including:Vacancies, interstitials, and impurities (especially hydrogen)Negative bias temperature instabilitiesDefects in ultrathin oxides (SiO2 and silicon oxynitride)Take A Proactive Approach The authors condense decades of experience and perspectives of noted experimentalists and theorists to characterize defect properties and their impact on microelectronic devices. They identify the defects, offering solutions to avoid them and methods to detect them. These include the use of 3-D imaging, as well as electrical, analytical, computational, spectroscopic, and state-of-the-art microscopic methods. This book is a valuable look at challenges to come from emerging materials, such as high-K gate dielectrics and high-mobility substrates being developed to replace Si02 as the preferred gate dielectric material, and high-mobility substrates
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| 24. |
- Janzén, Erik, 1954-, et al.
(författare)
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Material aspects on SiC
- 2005
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 25. |
- Janzén, Erik, 1954-, et al.
(författare)
-
The Silicon vacancy in SiC
- 2009
-
Konferensbidrag (refereegranskat)abstract
- A model is presented for the silicon vacancy in SiC. The previously reported photoluminescence spectra in 4H and 6H SiC attributed to the silicon vacancy are in this model due to internal transitions in the negative charge state of the silicon vacancy. The magnetic resonance signals observed are due to the initial and final states of these transitions.
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| 26. |
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| 27. |
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| 28. |
- Meyer, B. K., et al.
(författare)
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Optically detected cyclotron resonance investigations on 4H and 6H SiC : Band-structure and transport properties
- 2000
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 61:7, s. 4844-4849
-
Tidskriftsartikel (refereegranskat)abstract
- We present experimental data on the band-structure and high-mobility transport properties of 6H and 4H-SiC epitaxial films based on optically detected cyclotron resonance investigations. From the orientational dependence of the electron effective mass in 6H-SiC we obtain direct evidence for the camels back nature of the conduction band between the M and L points. The broadening of the resonance signal in 4H-SiC as a function of temperature is used to extract information on electron mobilities and to conclude on the role of the different scattering mechanisms. Under high microwave powers an enhancement of the electron effective mass is found which is explained by a coupling of the electrons with longitudinal optical phonons. ⌐2000 The American Physical Society.
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| 29. |
- Nagy, Roland, et al.
(författare)
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Quantum Properties of Dichroic Silicon Vacancies in Silicon Carbide
- 2018
-
Ingår i: Physical Review Applied. - 2331-7019. ; 9:3
-
Tidskriftsartikel (refereegranskat)abstract
- Although various defect centers have displayed promise as either quantum sensors, single photon emitters, or light-matter interfaces, the search for an ideal defect with multifunctional ability remains open. In this spirit, we study the dichroic silicon vacancies in silicon carbide that feature two well-distinguishable zero-phonon lines and analyze the quantum properties in their optical emission and spin control. We demonstrate that this center combines 40% optical emission into the zero-phonon lines showing the contrasting difference in optical properties with varying temperature and polarization, and a 100% increase in the fluorescence intensity upon the spin resonance, and long spin coherence time of their spin-3/2 ground states up to 0.6 ms. These results single out this defect center as a promising system for spin-based quantum technologies.
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| 30. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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A complex defect related to the carbon vacancy in 4H and 6H SiC
- 1999
-
Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T79, s. 46-49
-
Tidskriftsartikel (refereegranskat)abstract
- Electron paramagnetic resonance (EPR) was used to study defects in 4H and 6H SiC irradiated with 2.5 MeV electrons at room temperature. When the dose of irradiation reaches ~ 5 × 1017 electrons/cm2, an EPR spectrum appears. In both 4H and 6H SiC, the defect associated with this spectrum has C1h symmetry with an effective electron spin S = 1 and an isotropic g-value of 2.0063 ± 0.0002. The crystal-field parameter was determined as D = 1.65 and D = 1.67 GHz for 4H and 6H SiC, respectively. The principal crystal-field axis lies in the (11bar 20) plane and makes an angle of ~ 46° with the c-axis for both polytypes. A clear hyperfine structure from 29Si due to the interaction with four nearest silicon neighbours was observed, confirming that the defect is related to the carbon vacancy. The similarity in all respects including the annealing behaviour of the spectrum in both polytypes suggests that it belongs to the same defect. Based on the formation and its electronic structure, the defect is suggested to be a complex with one of the components being the carbon vacancy.
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| 31. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
-
Carbon-vacancy related defects in 4H- and 6H-SiC
- 1999
-
Ingår i: Materials Science and Engineering B, Vol. 61-62. - : Elsevier. ; , s. 202-
-
Konferensbidrag (refereegranskat)abstract
- Electron paramagnetic resonance (EPR) was used to study intrinsic defects in 4H- and 6H-SiC irradiated with 2.5 MeV electrons with doses ranging from 1×1017 to 2×1018 cm−2. In p-type 4H- and 6H-SiC, the dominant EPR signal, labeled EI1, associates with a defect centre having a low symmetry and an effective electron spin S=1/2. For both polytypes, its g-tensor was determined as gz=2.0015, gx=1.9962 and gy=2.0019, where gz and gx lie in the (11Image 0) plane and the z-axis makes an angle not, vert, similar41 degrees with the c-axis. Hyperfine interaction with a 29Si atom located at two equivalent sites in the nearest neighbour shell was detected, confirming that the defect resides at the carbon site. In heavily irradiated 4H- and 6H-SiC, a new EPR spectrum having an electron spin S=1, labeled EI3, was observed. In both polytypes, the EI3 centre has a low symmetry, an isotropic g-value of 2.0063 and a fine structure parameter |D|not, vert, similar5.5×10−2 cm−1. The observed hyperfine interaction with four 29Si atoms in the nearest neighbour shell confirms the involvement of the carbon vacancy in the defect. The defect is suggested to be a complex centre involving a carbon vacancy.
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| 32. |
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| 33. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Common point defects in as-grown ZnO substrates studied by optical detection of magnetic resonance
- 2008
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Ingår i: Journal of Crystal Growth, Vol. 310. - : Elsevier BV. - 0022-0248. ; , s. 1006-1009
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Konferensbidrag (refereegranskat)abstract
- Defects in as-grown commercial zinc oxide (ZnO) substrates were studied by photoluminescence and optical detection of magnetic resonance (ODMR). In addition to the Zn vacancy and shallow donor centers, we observed several ODMR centers with spin S=1/2, labeled LU1-LU4. Among these, the axial LU3 and non-axial LU4 centers were detected in all studied samples. The ODMR signals of LU3/LU4 were found to be drastically increased after electron irradiation. The preliminary result indicates that these common ODMR centers in as-grown ZnO are related to intrinsic defects. © 2007 Elsevier B.V. All rights reserved.
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| 34. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Cyclotron resonance studies of effective masses and band structure in SiC
- 2004
-
Ingår i: Silicon Carbide: Recent Major Advances. - Berlin, Heidelberg : Springer Verlag. - 9783540404583 - 3540404589 ; , s. -899
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- 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. The book is divided into five main categories: theory, crystal growth, characterization, processing and devices. Every attempt has been made to make the articles as up-to-date as possible and assure the highest standards of accuracy. As was the case for earlier SiC books, many of the articles will be relevant a decade from now so that this book will take its place next to the earlier work as a permanent and essential reference volume.
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| 35. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
-
Deep levels and carrier compensation in V-doped semi-insulating 4H-SiC
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:20
-
Tidskriftsartikel (refereegranskat)abstract
- Electron paramagnetic resonance was used to study semi-insulating (SI) 4H-SiC substrates doped with vanadium (V) in the range of 5.5× 1015 -1.1× 1017 cm-3. Our results show that the electrical activation of V is low and hence only in heavily V-doped 4H-SiC, vanadium is responsible for the SI behavior, whereas in moderately V-doped substrates, the SI properties are thermally unstable and determined by intrinsic defects. We show that the commonly observed thermal activation energy Ea ∼1.1 eV in V-doped 4H-SiC may be related to deep levels of the carbon vacancy. © 2007 American Institute of Physics.
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| 36. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Deep Levels Responsible for Semi-insulating Behaviour in Vanadium-doped 4H-SiC Substrates
- 2009
-
Ingår i: Materials Science Forum, Vols. 600-603. - : Trans Tech Publications. ; , s. 401-404
-
Konferensbidrag (refereegranskat)abstract
- Semi-insulating (SI) 4H-SiC substrates doped with vanadium (V) in the range 5.5×1015 –1.1×1017 cm–3 were studied by electron paramagnetic resonance. We show that only in heavily V-doped 4H-SiC vanadium is responsible for the SI behavior, whereas in moderate V-doped substrates with the V concentration comparable or slightly higher than that of the shallow N donor or B acceptor, the SI properties are thermally unstable and determined by intrinsic defects. The results show that the commonly observed thermal activation energy Ea~1.1 eV in V-doped 4H-SiC, which was previously assigned to the single acceptor V4+/3+ level, may be related to deep levels of the carbon vacancy. Carrier compensation processes involving deep levels of V and intrinsic defects are discussed and possible thermal activation energies are suggested.
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| 37. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
-
Defects and carrier compensation in semi-insulating 4H-SiC substrates
- 2007
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 75:15
-
Tidskriftsartikel (refereegranskat)abstract
- Electron paramagnetic resonance (EPR) studies revealed that vacancies (VC and VSi), carbon vacancy-antisite pairs (VC CSi) and the divacancy (VC VSi) are common defects in high-purity semi-insulating (HPSI) 4H-SiC substrates. Their concentrations and some of their deep acceptor levels were estimated by EPR and photoexcitation EPR. The commonly observed thermal activation energies, Ea ∼0.8-0.9 eV, ∼1.1 eV, ∼1.25-1.3, and ∼1.5 eV, as determined from the temperature dependence of the resistivity, in different types of HPSI substrates were associated to different deep acceptor levels of VSi, VC, VC CSi, and VC VSi. The annealing behavior of these vacancy-related defects and their interaction at high temperatures (up to 1600°C) in HPSI materials were studied. Carrier compensation processes were proposed to explain the observed change of the thermal activation energy due to high temperature annealing. VC and VC VSi were suggested to be suitable defects for controlling the SI properties whereas the incorporation of VSi and VC CSi during the crystal growth or processing should be avoided for achieving stable HPSI materials. © 2007 The American Physical Society.
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| 38. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Defects and impurities in β-Ga2O3
- 2019
-
Ingår i: Ultra-Wide Bandgap Semiconductor Materials. - : Elsevier. - 9780128154687 - 9780128172568 ; , s. 331-345
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 39. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Defects in high-purity semi-insulating SiC
- 2004
-
Ingår i: Mater. Sci. Forum, Vol. 457-460. - : Trans Tech Publications Inc.. ; , s. 437-
-
Konferensbidrag (refereegranskat)
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| 40. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
-
Defects introduced by electron-irradiation at low temperatures in SiC
- 2009
-
Ingår i: Materials Science Forum Vols. 615-617. - : Trans Tech Publicarions. - 9780878493340 ; , s. 377-380
-
Konferensbidrag (refereegranskat)abstract
- Defects introduced by electron irradiation at ~80-100 K in 3C-, 4H- and 6H-SiC were studied by electron paramagnetic resonance (EPR). A number of EPR spectra, labelled LE1-10, were detected. Combining EPR and supercell calculations, we will show that the LE1 center in 3C-SiC with C2v symmetry and an electron spin S=3/2 is related to the (VSi-Sii)3+ Frenkel pair between the silicon vacancy and a second neighbour Sii interstitial along the <100> direction. Results on other centers, possibly also related to interstitials, are discussed.
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| 41. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
-
Divacancy in 4H-SiC
- 2006
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 96:5, s. 055501-1-055501-4
-
Tidskriftsartikel (refereegranskat)abstract
- Electron paramagnetic resonance and ab initio supercell calculations suggest that the P6/P7 centers, which were previously assigned to the photoexcited triplet states of the carbon vacancy-antisite pairs in the double positive charge state, are related to the triplet ground states of the neutral divacancy. The spin density is found to be located mainly on three nearest C neighbors of the silicon vacancy, whereas it is negligible on the nearest Si neighbors of the carbon vacancy.
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| 42. |
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| 43. |
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| 44. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
-
Electron-paramagnetic-resonance studies of defects in electron-irradiated p-type 4H and 6H SiC
- 1999
-
Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 273-274, s. 655-658
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Tidskriftsartikel (refereegranskat)abstract
- Defects in p-type 4H and 6H SiC irradiated by 2.5 MeV electrons were studied by electron paramagnetic resonance (EPR). Two anisotropic EPR spectra, labeled I and II, were observed in both 4H and 6H SiC. These spectra demonstrating triclinic symmetry of the center can be described by an effective electron spin S=1/2. The angle α between the direction of the principal gz of the g-tensors and the c-axis is determined as 63° and 50° for spectra I and II, respectively. In the 6H polytype, a third also similar EPR spectrum was detected. Based on their similarity in the electronic structure (electron spin, symmetry, g values), annealing behavior and temperature dependence, these spectra are suggested to be related to the same defect occupying different inequivalent lattice sites in 4H and 6H SiC. A pair between a silicon vacancy and an interstitial is a possible model for the defect.
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| 45. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Electronic structure of deep defects in SiC
- 2004
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Ingår i: Silicon Carbide: Recent Major Advances. - Berlin, Heidelberg : Springer Verlag. - 9783540404583 - 3540404589 ; , s. -899
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- 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. The book is divided into five main categories: theory, crystal growth, characterization, processing and devices. Every attempt has been made to make the articles as up-to-date as possible and assure the highest standards of accuracy. As was the case for earlier SiC books, many of the articles will be relevant a decade from now so that this book will take its place next to the earlier work as a permanent and essential reference volume.
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| 46. |
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| 47. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Hole effective masses in 4H SiC
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 61:16
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Tidskriftsartikel (refereegranskat)abstract
- Optically detected cyclotron resonance (ODCR) at X-band frequency (~9.23 GHz) was used to study hole effective masses in 4H SiC. In addition to the known ODCR signal related to the cyclotron resonance (CR) of electrons we have observed an ODCR peak at a higher magnetic field, which is attributed to the CR of holes. In the vicinity of the maximum of the uppermost valence band, the constant energy surface can be considered as an ellipsoid with the principal axis along the c axis and the effective masses of the holes were determined as mh? = (0.66▒0.02)m0 and mh?=(1.75▒0.02)m0. The influence of the polaron coupling effect on the effective mass values in 4H SiC is discussed. ⌐ 2000 The American Physical Society.
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| 48. |
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| 49. |
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