| 1. |
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| 2. |
- 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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| 3. |
- Andersson, Linda, 1973, et al.
(författare)
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PLD1 and ERK2 regulate cytosolic lipid droplet formation
- 2006
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Ingår i: J Cell Sci. ; 119:Pt 11, s. 2246-57
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Tidskriftsartikel (refereegranskat)abstract
- We have previously uncovered roles for phospholipase D (PLD) and an unknown cytosolic protein in the formation of cytosolic lipid droplets using a cell-free system. In this report, PLD1 has been identified as the relevant isoform, and extracellular signal-regulated kinase 2 (ERK2) as the cytosolic protein. Increased expression of PLD1 increased lipid droplet formation whereas knockdown of PLD1 using siRNA was inhibitory. A role for ERK2 in basal lipid droplet formation was revealed by overexpression or microinjection, and ablation by siRNA knockdown or pharmacological inhibition. Similar manipulations of other Map kinases such as ERK1, JNK1 or JNK2 and p38alpha or p38beta were without effect. Insulin stimulated the formation of lipid droplets and this stimulation was inhibited by knockdown of PLD1 (by siRNA) and by inhibition or knockdown (by siRNA) of ERK2. Inhibition of ERK2 eliminated the effect of PLD1 on lipid droplet formation without affecting PLD1 activity, suggesting that PLD1 functions upstream of ERK2. ERK2 increased the phosphorylation of dynein which increased the amount of the protein on ADRP-containing lipid droplets. Microinjection of antibodies to dynein strongly inhibited the formation of lipid droplets, demonstrating that dynein has a central role in this formation. Thus dynein is a possible target for ERK2.
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| 4. |
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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. |
- Eriksson, Leif, 1970, et al.
(författare)
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ALOS PALSAR Calibration and Validation Results from Sweden
- 2007
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Ingår i: IEEE Geoscience and Remote Sensing Symposium (IGARSS 2007), Barcelona, Spain, July 23-27, 2007. ; DOI: 10.1109/IGARSS.2007.4423115, s. 1589-1592
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In 2006 calibration activities for ALOS PALSAR wereconducted in Sweden. Four five-metre trihedral corner reflectorsand three smaller dihedral reflectors were deployed and operatedduring eight months. 23 PALSAR scenes were acquired over thecalibration site allowing an evaluation of the quality and temporalstability of the data. Results show that the co-polarized datahave been stable during the whole calibration period with variationsin the trihedral responses lower than 0.7 dB. The measuredresolution in azimuth was 4.4 m and in slant range 4.7 m forsingle polarization images and 9.5 m for polarimetric data. Forthe cross-polarized data large variations in the dihedral responseswere found. It is assumed that this is caused by a larger sensitivityto pointing errors. For the polarimetric data, estimation ofFaraday rotation gave values ranging from 0.1º to 3º.
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| 7. |
- Falk Johansson, Marcus, et al.
(författare)
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A comparison of spouse and non-spouse carers of people with dementia : a descriptive analysis of Swedish national survey data
- 2021
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Ingår i: BMC Geriatrics. - : BioMed Central. - 1471-2318. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundBeing an informal carer of a person with dementia (PwD) can have a negative effect on the carer's health and quality of life, and spouse carers have been found to be especially vulnerable. Yet relatively little is known about the care provided and support received by spouse carers. This study compares spouse carers to other informal carers of PwDs regarding their care provision, the support received and the psychosocial impact of care.MethodsThe study was a cross-sectional questionnaire-based survey of a stratified random sample of the Swedish population aged 18 or over. The questionnaire explored how much care the respondent provided, the support received, and the psychosocial impact of providing care. Of 30,009 people sampled, 11,168 (37.7%) responded, of whom 330 (2.95%) were informal carers of a PwD.ResultsIn comparison to non-spouse carers, spouse carers provided more care more frequently, did so with less support from family or the local authority, while more frequently experiencing negative impacts on their social life and psychological and physical health. Spouse carers also received more carer support and more frequently experienced a closeness in their relationship with the care-recipient.ConclusionsSpouse carers of PwD differed from non-spouse carers on virtually all aspects of their care situation. Policy and practice must be more sensitive to how the carer-care-recipient relationship shapes the experience of care, so that support is based on an understanding of the individual carer's actual needs and preferences rather than on preconceptions drawn from a generalised support model.
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| 8. |
- 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
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Ingår i: Materials Science Forum, vol. 556-557. - : Trans Tech Publications. ; , s. 371-
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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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| 9. |
- Gällström, Andreas, 1978-, et al.
(författare)
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Optical identification of Mo related deep level defect in 4H and 6H SiC
- 2009
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Ingår i: Materials Science Forum Vols. 615-617. - : Trans Tech Publications. ; , s. 405-408
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Konferensbidrag (refereegranskat)abstract
- The photoluminescence (PL) from the I 1 centre is observed in p-, n-type as well as in compensated samples, using above band gap excitation. The PL from I 1 in the two polytypes 4H and 6H is very similar, the difference being the position of the main peak, in 4H 1.1521 eV and 1.1057 eV in 6H. We here suggest I-1 to be Mo related based on intentional doping, SIMS results and comparison with earlier reports of Mo in SiC using magnetic resonance techniques. From PL measurements, we analyze the electron structure of the defect, and suggest it be the neutral Mo (4d2) residing on a Si site, the luminescence coming from the transition between the 3A2 multiplet of the first excited electronic configuration and the ground state 3A2.
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| 10. |
- Gällström, Andreas, 1978-, et al.
(författare)
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The Electronic Structure of the UD-4 defect in 4H, 6H and 15R SiC
- 2009
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Ingår i: Materials Science Forum, Vols. 600-603. - : Trans Tech Publications. ; , s. 397-400
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Konferensbidrag (refereegranskat)abstract
- The photoluminescence (PL) of the UD-4 defect is observed in semi-insulating bulk 4H, 6H and 15R SiC. In 4H and 6H SiC the UD-4 defect consists of two families of no-phonon (NP) lines, Ua and Ub, and in 15R SiC it consists of three families, Ua, Ub and U15R. The Ua family in 4H, 6H and 15R all show similar temperature behavior with higher energy NP lines becomming observable at higher temperatures. In the case of the Ub and U15R families, a luminescence line with lower energy than the prominent luminescence line appears at higher temperatures. The polarization and Zeeman measurements suggest that the defect has C3v symmetry.
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| 11. |
- Hahn, S., et al.
(författare)
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Contact-Less Electrical Defect Characterization of Semi-Insulating 6H-SiC Bulk Material
- 2009
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Ingår i: Materials Science Forum Vols. 600-603. - : Trans Tech Publications. ; , s. 405-408
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Konferensbidrag (refereegranskat)abstract
- The novel technique microwave detected photo induced current transient spectroscopy (MD-PICTS) was applied to semi-insulating 6H-SiC in order to investigate the properties of inherent defect levels. Defect spectra can be obtained in the similar way to conventional PICTS and DLTS. However, there is no need for contacting the samples, which allows for non-destructive and spatially resolved electrical characterization. This work is focused on the investigation of semi-insulating 6H-SiC grown under different C/Si-ratios. In the corresponding MD-PICTS spectra several shallow defect levels appear in the low temperature range. However the peak assignment needs further investigation. Additionally different trap reemission dynamics are obtained for higher temperatures, which are supposed to be due to different compensation effects.
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| 12. |
- Janzén, Erik, 1954-, et al.
(författare)
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Defects in SiC
- 2004
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Janzén, Erik, 1954-, et al.
(författare)
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Defects in SiC
- 2008
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Ingår i: Defects in Microelectronic Materials and Devices. - : Taylor and Francis LLC. ; , s. 770-
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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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| 14. |
- Janzén, Erik, 1954-, et al.
(författare)
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The Silicon vacancy in SiC
- 2009
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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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| 15. |
- Kakanakova-Georgieva, Anelia, 1970-, et al.
(författare)
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Growth of AlN films by hot-wall CVD and sublimation techniques : Effect of growth cell pressure
- 2002
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Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 1469-1472
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Konferensbidrag (refereegranskat)abstract
- Aluminum nitride (AlN) films were grown on off-axis, Si-terminated 4H-SiC substrates by hot-wall CVD and sublimation techniques. The films were investigated by Infrared reflectance, Optical microscopy, Energy Dispersive X-ray analysis and Cathodoluminescence in a Scanning Electron Microscope with respect to their thickness, morphological, compositional and luminescence properties, in order to examine the influence of the growth cell pressure in either of the two deposition methods. Good quality thick AlN films were obtained by hot-wall CVD at temperature of 1200degreesC and reduced pressure of 100 mbar as reflected in the near stoichiometric N/Al ratio in these layers and in the appearance of the characteristic AlN near band edge emission. The AlN sublimation grown films at temperature of 2100degreesC suffered from island growth irrespective of the background pressure. The supersaturation conditions that affect strongly the growth mode became more favorable when the temperature was reduced to 1900degreesC.
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| 16. |
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| 17. |
- Magnusson, Björn, 1970-, et al.
(författare)
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Optical Characterization of Deep Level Defects in SiC
- 2005
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Ingår i: Materials Science Forum, Vols. 483-485. - 0878499636 ; , s. 341-346
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Konferensbidrag (refereegranskat)abstract
- Deep levels in 4H- and 6H-SiC are characterized by FTIR spectroscopy. Vanadium, chromium and the silicon vacancy related center are listed together with the unidentified defects with emission and absorption in the near IR region. We suggest the UD-1, UD-3 and I-1 to be impurity related while the UD-2 and UD-4 to be intrinsic defects based on annealing behavior and the possibility to create the defect with irradiation. We have also tentatively assigned a new defect center around 1.0 eV to the carbon vacancy-antisite pair instead of the earlier assignment to the UD- 2 defect in 4H-SiC. We have shown that to get more information about the SiC samples a combination of absorption and luminescence techniques are very useful. Further, the use of below bandgap selective excitation is necessary to obtain more information about the defects present in the sample. FTIR absorption and luminescence measurements are useful tools to characterize deep levels important for both semi-insulating material as well as low doped conducting material where the free carrier lifetime is limited by deep levels.
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| 18. |
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| 19. |
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| 20. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Deep levels and carrier compensation in V-doped semi-insulating 4H-SiC
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:20
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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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| 21. |
- 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
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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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| 22. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Defects and carrier compensation in semi-insulating 4H-SiC substrates
- 2007
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 75:15
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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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| 23. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Defects in high-purity semi-insulating SiC
- 2004
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Ingår i: Mater. Sci. Forum, Vol. 457-460. - : Trans Tech Publications Inc.. ; , s. 437-
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Konferensbidrag (refereegranskat)
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| 24. |
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| 25. |
- 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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| 26. |
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| 27. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Photoluminescence and Zeeman effect in chromium-doped 4H and 6H SiC
- 1999
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 86:8, s. 4348-
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Tidskriftsartikel (refereegranskat)abstract
- Photoluminescence (PL) and Zeeman effect measurements in near-infrared luminescence bands in Cr-doped 4H and 6H SiC are presented. The PL spectrum consists of two no-phonon lines (NPLs) at 1.1583 and 1.1898 eV in 4H SiC and three NPLs at 1.1556, 1.1797, and 1.1886 eV in 6H SiC. The observed Zeeman splittings and temperature dependence studies reveal the spin triplet of the ground state and the orbital doublet structure of the excited state of the Cr-related center. All the triplets have almost isotropic g values close to 2 with trigonal symmetry and small zero-field splitting values D. In contrast, the effective g values of the excited state of the center are very anisotropic with g|| in the range of 0.22-0.64 and g[perpendicular] = 0 for different NPLs in both polytypes. Based on the Zeeman results, the PL is attributed to the internal transition 1E(D)-->3A2(F) within the d shell of a substitutional, neutral chromium (Cr4 + ) in the 3d2 electronic configuration.
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| 28. |
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| 29. |
- Stensköld, Eva, 1970-
(författare)
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Att berätta en senneolitisk historia : Sten och metall i södra Sverige 2350-1700 f. Kr
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis discusses aspects of how the Late Neolithic society in southern Sweden changed through the use of metal. Particular focus is on how the different categories of the material culture were utilized in this process – the Late Neolithic flint daggers and objects of stone imitating objects of metal.The presence of metal in the Late Neolithic society is discussed and explicated by the correlation of metal objects to objects imitating metal. Imitations are not perceived as passive copies, but as a continuing dialogue between artefacts. These imitations are viewed as filling a function wherein they help to prepare society to express social and political processes in a different material, as a way to meet and relate to the new world-view that the metal objects implied through their existence.The difference between resharpened and non-resharpened flint daggers is explored through a variety of quantitative and qualitative analyses. There appears to have been two differing rules of deposition of the two types of flint daggers in the Late Neolithic society. Resharpened and non-resharpened flint daggers thus seem to relate to different societal spheres of significance in society.It is suggested that the flint daggers were used in varying forms of ritual body modification practices, as tools for alteration of bodily appearance. These rituals can be termed passage rituals – rituals connected to the individual’s journey through her life-cycle. The resharpening of the dagger blade is then to be understood as a ceremonial resharpening, a ritual remaking of the dagger.During the Late Neolithic, gallery graves, mortuary houses and votive offerings were used to express a connection to an older, ancestral ideology, based on communal rituals. At the same time a new ideology was expressed through the use of individual earth graves and ritual body modification practices. The human body, previously attributed an ancestral role, was now used as a medium of classification, signification and individual expression. The ritual practice works both as a societal regulator and as a way for individuals to express themselves in relation to others.The ritual body modification practices, manifested in different rituals of passage, may have been a way for individuals to relate to the changes in society during the course of the Late Neolithic.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Wagner, Matthias, 1969-, et al.
(författare)
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Electronic structure of the neutral silicon vacancy in 4H and 6H SiC
- 2000
-
Ingår i: Physical review. B, Condensed matter and materials physics. - 2469-9950. ; 62:24, s. 16555-16560
-
Tidskriftsartikel (refereegranskat)abstract
- Detailed information about the electronic structure of the lowest-lying excited states and the ground state of the neutral silicon vacancy in 4H and 6H SiC has been obtained by high-resolution photoluminescence (PL), PL excitation (PLE), and Zeeman spectroscopy of both PL and PLE. The excited states and the ground states involved in the characteristic luminescence of the defect with no-phonon (NP) lines at 1.438 and 1.352 eV in 4H SiC and 1.433, 1.398, and 1.368 eV in 6H SiC are shown to be singlets. The orbital degeneracy of the excited states is lifted by the crystal field for the highest-lying NP lines corresponding to one of the inequivalent lattice sites in both polytypes, leading to the appearance of hot lines at slightly higher energies. Polarization studies of the NP lines show a different behavior for the inequivalent sites. A comparison of this behavior in the two polytypes together with parameters from spin resonance studies provides useful hints for the assignment of the no-phonon lines to the inequivalent sites. In strained samples an additional fine structure of the NP lines can be resolved. This splitting may be due to strain variations in the samples.
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| 35. |
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| 36. |
- Wagner, Matthias, 1969-, et al.
(författare)
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Photoluminescence upconversion in 4H-SiC
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:14, s. 2547-
-
Tidskriftsartikel (refereegranskat)abstract
- Efficient photoluminescence upconversion is observed in 4H-SiC samples containing both the UD-3 defect and the titanium impurity. In this process, the titanium photoluminescence emission with no-phonon (NP) lines at 2.848 eV (A0) and 2.789 eV (B0) can be excited by tuning the laser to the NP line of UD-3 at 1.356 eV. In samples containing either only UD-3 or only titanium, a different photoluminescence upconversion process can be observed, which occurs at photon energies higher than ~1.5 eV without exhibiting sharp features. At least one of the two processes generates both free electrons and free holes and can, therefore, be a candidate for an important recombination channel.
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| 37. |
- Wagner, Matthias, 1969-, et al.
(författare)
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Zeeman spectroscopy of the neutral silicon vacancy in 6H and 4H SiC
- 1999
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Ingår i: Physica B. Vol. 273-274. - : Elsevier. ; , s. 663-
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Konferensbidrag (refereegranskat)abstract
- High-resolution photoluminescence (PL) and PL excitation (PLE) spectroscopy has been employed to reveal the electronic structure of the neutral silicon vacancy in 6H and 4H SiC. The defect gives rise to characteristic PL emissions with three no-phonon lines in 6H SiC and two in 4H SiC at around 1.4 eV. All of the no-phonon lines are shown to arise from transitions between singlet (S=0) excited states and singlet ground states. Nevertheless, optically detected magnetic resonance (ODMR) signals typical for a spin triplet (S=1) configuration can be obtained when monitoring the emission under resonant excitation. This observation can be explained by non-radiative recombination via a lower lying excited triplet state. In strained samples all no-phonon PL lines are split into a series of lines. For the highest energy lines the main splitting can be attributed to lifting of the orbital degeneracy of the excited states, the additional broadening or splitting is probably due to a strain distribution in the samples.
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| 38. |
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