liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Lindefelt, Ulf
Publications (10 of 23) Show all publications
Nguyen, S. T., Persson, C., Lindefelt, U., Chen, W., Janzén, E., Meyer, B. K. & Hofmann, D. M. (2004). Cyclotron resonance studies of effective masses and band structure in SiC. In: W.J. Choyke, H. Matsunami, G. Pensl (Ed.), Silicon Carbide: Recent Major Advances: . Berlin, Heidelberg: Springer Verlag
Open this publication in new window or tab >>Cyclotron resonance studies of effective masses and band structure in SiC
Show others...
2004 (English)In: Silicon Carbide: Recent Major Advances / [ed] W.J. Choyke, H. Matsunami, G. Pensl, Berlin, Heidelberg: Springer Verlag , 2004, p. -899Chapter in book (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Berlin, Heidelberg: Springer Verlag, 2004
Series
Advanced texts in physics, ISSN 1439-2674
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-45172 (URN)79897 (Local ID)978-3-540-40458-3 (ISBN)3-540-40458-9 (ISBN)79897 (Archive number)79897 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-10-28Bibliographically approved
Iwata, H., Lindefelt, U., Oberg, S. & Briddon, P. (2003). A new type of quantum wells: Stacking faults in silicon carbide. Microelectronics Journal, 34(5-8)
Open this publication in new window or tab >>A new type of quantum wells: Stacking faults in silicon carbide
2003 (English)In: Microelectronics Journal, ISSN 0026-2692, Vol. 34, no 5-8, p. 371-374Conference paper, Published paper (Other academic)
Abstract [en]

We report on a new type of quantum wells with the width as thin as 10Å, which are composed of SiC only, and consequently have ideal interfaces. These quantum wells are actually stacking faults in SiC. Certain types of stacking faults in SiC polytypes create small 3C-like regions, where the stacking sequences along the c-axis become locally cubic in the hexagonal host crystals. Since the conduction band offsets between the cubic and hexagonal polytypes are very large with the conduction band minima of 3C-SiC lower than that of the other polytypes, such thin 3C inclusions can introduce locally lower conduction bands, thus acting as quantum films perpendicular to the c-axis. One mechanism for the occurrence of stacking faults in the perfect SiC single crystals is the motion of partial dislocations in the basal planes, the partial dislocations leaving behind stacking fault regions. © 2003 Elsevier Science Ltd. All rights reserved.

Keywords
Quantum wells, Silicon carbide, Stacking faults
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46640 (URN)10.1016/S0026-2692(03)00027-2 (DOI)
Available from: 2009-10-11 Created: 2009-10-11
Iwata, H., Lindefelt, U., Oberg, S. & Briddon, P. (2003). Ab initio study of 3 C inclusions and stacking fault-stacking fault interactions in 6H-SiC. Journal of Applied Physics, 94(8), 4972-4979
Open this publication in new window or tab >>Ab initio study of 3 C inclusions and stacking fault-stacking fault interactions in 6H-SiC
2003 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 94, no 8, p. 4972-4979Article in journal (Refereed) Published
Abstract [en]

A ab initio study of 3 C inclusions and stacking fault-stacking fault interactions in 6H-SiC was presented. The electronic structures and the total energies of 6H-SiC single crystals that contain one, two, three and four stacking faults were studied. The possibility of local hexagonal to cubic polytypic transformations was discussed in light of the formation energy and quantum-well action.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46458 (URN)10.1063/1.1610772 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Iwata, H., Lindefelt, U., Oberg, S. & Briddon, P. (2003). Cubic polytype inclusions in 4H-SiC. Journal of Applied Physics, 93(3), 1577-1585
Open this publication in new window or tab >>Cubic polytype inclusions in 4H-SiC
2003 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 3, p. 1577-1585Article in journal (Refereed) Published
Abstract [en]

The multiple stacking faults in 4H-SiC, leading to narrow 3C polytype inclusions along the hexagonal c direction, were discussed. The stacking fault energies for successive stacking faults were calculated. The analysis showed that the stacking fault energy for the two stacking faults in adjacent basal planes was reduced by approximately a factor of 4 relative to that of one isolated stacking fault.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46730 (URN)10.1063/1.1534376 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Jacobson, H., Birch, J., Hallin, C., Henry, A., Yakimova, R., Tuomi, T., . . . Lindefelt, U. (2003). Doping-induced strain in N-doped 4H-SiC crystals. Applied Physics Letters, 82(21), 3689-3691
Open this publication in new window or tab >>Doping-induced strain in N-doped 4H-SiC crystals
Show others...
2003 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 21, p. 3689-3691Article in journal (Refereed) Published
Abstract [en]

Stress in epitaxial layers due to crystal lattice mismatch directly influences the growth, structure, and basic electrophysical parameters of epitaxial films and also to a large extent the degradation processes in semiconductor devices. In this letter, we present a theoretical model for calculating the induced lattice compression due to N doping and the critical thickness concerning formation of misfit dislocations in homoepitaxial 4H–SiC layers with different N-doping levels. For example: The model predicts that substrates with a N concentration of 3×1019 cm-3 induce misfit dislocations when the epilayer thickness reaches ∼10 μm. Also, the N-doping concentration in the 1×1018–1×1019 cm-3 range yields a strain that not will cause misfit dislocactions at the substrate and epilayer interface until an epilayer thickness of 200–300 μm is reached. Supporting evidence of the induced lattice compression due to N doping have been done by synchrotron white-beam x-ray topography on samples with different N-doping levels and are compared with the predicted results from the model

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-62881 (URN)10.1063/1.1579120 (DOI)
Available from: 2010-12-06 Created: 2010-12-06 Last updated: 2017-12-11
Jacobson, H., Birch, J., Lindefelt, U., Hallin, C., Henry, A., Yakimova, R. & Janzén, E. (2003). Doping-related strain in n-doped 4H-SiC crystals. In: Materials Science Forum, Vols. 433-436. Paper presented at ECSCRM2002 (pp. 269-272). , 433-4
Open this publication in new window or tab >>Doping-related strain in n-doped 4H-SiC crystals
Show others...
2003 (English)In: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, p. 269-272Conference paper, Published paper (Refereed)
Abstract [en]

Stress in epitaxial layers due to crystal lattice mismatch directly influences growth, structure, and basic electro-physical parameters of epitaxial films and also to a large extent the degradation processes in semiconductor devices. In this paper we present a theoretical model for calculating the induced lattice compression due to N doping and the critical thickness concerning formation of misfit dislocations in homoepitaxial 4H-SiC layers with different N doping levels. For example: The model predicts that substrates with N concentration of 3E19 induce misfit dislocations when the epilayer thickness reaches similar to10 mum. Also, N doping concentration in the 1E18-1E19 range yields a strain that not will cause misfit dislocactions at the substrate and epilayer interface until an epilayer thickness of 200-300 mum is reached. Supporting evidence of the induced lattice compression due to N doping have been done by synchrotron white-beam x-ray topography on samples with different N doping level and are compared with the predicted results from the model.

Keywords
4H-SiC, doping, model, strain, synchrotron topography
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-48538 (URN)
Conference
ECSCRM2002
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2014-10-08
Iwata, H., Lindefelt, U., Oberg, S. & Briddon, P. (2003). Effective masses of two-dimensional electron gases around cubic inclusions in hexagonal silicon carbide. Physical Review B. Condensed Matter and Materials Physics, 68(24)
Open this publication in new window or tab >>Effective masses of two-dimensional electron gases around cubic inclusions in hexagonal silicon carbide
2003 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 24Article in journal (Refereed) Published
Abstract [en]

The main purpose of this article is to determine the two-dimensional effective mass tensors of electrons confined in thin 3C wells in hexagonal SiC, which is a first step in the understanding of in-plane electron motion in the novel quantum structures. We have performed ab initio band structure calculations, based on the density functional theory in the local density approximation, for single and multiple stacking faults leading to thin 3C-like regions in 4H- and 6H-SiC and deduced electron effective masses for two-dimensional electron gases around the cubic inclusions. We have found that electrons confined in the thin 3C-like layers have clearly heavier effective masses than in the perfect bulk 3C-SiC single crystal.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46293 (URN)10.1103/PhysRevB.68.245309 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Iwata, H., Lindefelt, U., Oberg, S. & Briddon, P. (2003). Energies and electronic properties of isolated and interacting twin boundaries in 3C-SiC, Si, and diamond. Physical Review B. Condensed Matter and Materials Physics, 68(11)
Open this publication in new window or tab >>Energies and electronic properties of isolated and interacting twin boundaries in 3C-SiC, Si, and diamond
2003 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 11Article in journal (Refereed) Published
Abstract [en]

First-principles calculations of twin boundaries in 3C-SiC, Si, and diamond are performed, based on the density-functional theory in the local density approximation. We have investigated the formation energies and electronic properties of isolated and interacting twin boundaries. It is found that in 3C-SiC, interacting twin boundaries which are separated by more than two Si-C bilayers are actually energetically more favorable, implying a relatively frequent appearance of these defects. The effect of the spontaneous polarization associated with the hexagonal symmetry around twin boundaries is also studied, and we have observed that the wave functions belonging to the conduction- and valence-band edge states in 3C-SiC tend to be localized almost exclusively on different sides of the faulted layers, while there is no such feature in Si or diamond.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47753 (URN)10.1103/PhysRevB.68.113202 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Lindefelt, U., Iwata, H., Oberg, S. & Briddon, P. (2003). Stacking faults in 3C-, 4H-, and 6H-SiC polytypes investigated by an ab initio supercell method. Physical Review B. Condensed Matter and Materials Physics, 67(15)
Open this publication in new window or tab >>Stacking faults in 3C-, 4H-, and 6H-SiC polytypes investigated by an ab initio supercell method
2003 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 67, no 15Article in journal (Refereed) Published
Abstract [en]

Recent attempts to make SiC diodes have revealed a problem with stacking fault expansion in the material, leading to unstable devices. In this paper, we present detailed results from a density-functional supercell calculation on the electronic structure of stacking faults which result from glide of Shockley partials in 3C-, 4H- and 6H-SiC. It was found [Phys. Rev. B 65, 033203 (2002)] that both types of stacking faults in 4H-SiC and two types of stacking faults in 6H-SiC give rise to band states, which are strongly localized (confined within around 10 Angstrom) in the direction orthogonal to the stacking fault plane. Based on estimates of the band offsets between different polytypes and a simple quantum-well theory, we show that it is possible to interpret this one-dimensional localization as a quantum-well confinement effect. We also find that the third type of stacking fault in 6H-SiC and the only stacking fault in 3C-SiC do not give rise to states clearly separated from the band edges, but instead give rise to rather strongly localized band states with energies very close to the band edges. We argue that these localized near band edge states are created by stacking fault induced changes in the dipole moment associated with the hexagonal symmetry. In addition, we have also calculated the stacking fault energies, using both the supercell method and the simpler ANNNI (axial next nearest-neighbor Ising) model. Both theories agree well with the low stacking fault energies found experimentally.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47803 (URN)10.1103/PhysRevB.67.155204 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Iwata, H., Lindefelt, U., Öberg, S. & Briddon, P. (2003). Stacking faults in silicon carbide. Paper presented at 22nd International Conference on Defects in Semiconductors (ICDS-22), Aarhus University, Aarhus, Denmark, Juli 28- August 01, 2003. Physica. B, Condensed matter, 340, 165-170
Open this publication in new window or tab >>Stacking faults in silicon carbide
2003 (English)In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 165-170Article in journal (Refereed) Published
Abstract [en]

We review of our theoretical work on various stacking faults in SiC polytypes. Since the discovery of the electronic degradation phenomenon in 4H-SiC p-i-n diodes, stacking faults in SiC have become a subject of intensive study around the globe. At the beginning of our research project, the aim was to find the culprit for the degradation phenomenon, but in the course of this work we uncovered a wealth of information for the general properties of stacking faults in SiC. An intuitive perspective to the diverse nature of stacking faults in SiC will be given in this conference report. (C) 2003 Published by Elsevier B.V.

Place, publisher, year, edition, pages
Elsevier, 2003
Keywords
stacking fault, dislocations, quantum well, solid-solid phase transition
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-46297 (URN)10.1016/j.physb.2003.09.045 (DOI)000188300200028 ()
Conference
22nd International Conference on Defects in Semiconductors (ICDS-22), Aarhus University, Aarhus, Denmark, Juli 28- August 01, 2003
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
Organisations

Search in DiVA

Show all publications