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Linnarsson, Margareta K.ORCID iD iconorcid.org/0000-0002-0292-224X
Alternative names
Publications (10 of 144) Show all publications
Suvanam, S. S., Usman, M., Martin, D., Yazdi, M. G., Linnarsson, M. K., Tempez, A., . . . Hallén, A. (2018). Improved interface and electrical properties of atomic layer deposited Al2O3/4H-SiC. Applied Surface Science, 433, 108-115
Open this publication in new window or tab >>Improved interface and electrical properties of atomic layer deposited Al2O3/4H-SiC
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 433, p. 108-115Article in journal (Refereed) Published
Abstract [en]

In this paper we demonstrate a process optimization of atomic layer deposited Al2O3 on 4H-SiC resulting in an improved interface and electrical properties. For this purpose the samples have been treated with two pre deposition surface cleaning processes, namely CP1 and CP2. The former is a typical surface cleaning procedure used in SiC processing while the latter have an additional weak RCA1 cleaning step. In addition to the cleaning and deposition, the effects of post dielectric annealing (PDA) at various temperatures in N2O ambient have been investigated. Analyses by scanning electron microscopy show the presence of structural defects on the Al2O3 surface after annealing at 500 and 800 °C. These defects disappear after annealing at 1100 °C, possibly due to densification of the Al2O3 film. Interface analyses have been performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight medium energy ion scattering (ToF MEIS). Both these measurements show the formation of an interfacial SiOx (0 < x < 2) layer for both the CP1 and CP2, displaying an increased thickness for higher temperatures. Furthermore, the quality of the sub-oxide interfacial layer was found to depend on the pre deposition cleaning. In conclusion, an improved interface with better electrical properties is shown for the CP2 sample annealed at 1100 °C, resulting in lower oxide charges, strongly reduced flatband voltage and leakage current, as well as higher breakdown voltage.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
4H-SiC, Al2O3, High-K dielectric, Interface trap densities, Annealing, Atomic layer deposition, Cleaning, Deposition, Optimization, Scanning electron microscopy, Silicon carbide, Surface cleaning, Surface defects, Atomic layer deposited, Interface analysis, Interface trap density, Medium energy ion scattering, Structural defect, Surface cleaning procedure, X ray photoelectron spectroscopy
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-223127 (URN)10.1016/j.apsusc.2017.10.006 (DOI)000418883800014 ()2-s2.0-85031746823 (Scopus ID)
Funder
Swedish Research Council, D0674701
Note

QC 20180327

Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-04-11Bibliographically approved
Linnarsson, M. K., Hallén, A., Khartsev, S., Suvanam, S. S. & Usman, M. (2017). Interface between Al2O3 and 4H-SiC investigated by time-of-flight medium energy ion scattering. Journal of Physics D: Applied Physics, 50(49), Article ID 495111.
Open this publication in new window or tab >>Interface between Al2O3 and 4H-SiC investigated by time-of-flight medium energy ion scattering
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2017 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 49, article id 495111Article in journal (Refereed) Published
Abstract [en]

The formation of interfacial oxides during heat treatment of dielectric films on 4H-SiC has been studied. The 4H-SiC surface has been carefully prepared to create a clean and abrupt interface to Al2O3. An amorphous, 3 nm thick, Al2O3 film has been prepared on 4H-SiC by atomic layer deposition and rapid thermal annealing was then performed in N2O ambient at 700 degrees C and 1100 degrees C during 1 min. The samples were studied by time-of-flight medium energy ion scattering (ToF-MEIS), with sub-nanometer depth resolution and it is seen that, at both annealing temperatures, a thin SiOx (1 <= x <= 2) is formed at the interface. Our results further indicate that carbon remains in the silicon oxide in samples annealed at 700 degrees C. Additional electrical capacitance voltage measurements indicate that a large concentration of interface traps is formed at this temperature. After 1100 degrees C annealing, both MEIS and XRD measurements show that these features disappear, in accordance with electrical data.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017
Keywords
ALD, ToF-MEIS, 4H-SiC, Al2O3, interface
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-219324 (URN)10.1088/1361-6463/aa9431 (DOI)000415834100006 ()2-s2.0-85039788159 (Scopus ID)
Funder
Swedish Research Council, E0510501; D0674701
Note

QC 20171205

Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2018-01-11Bibliographically approved
Linnarsson, M. K., Suvanam, S. S., Vines, L. & Hallén, A. (2016). Alkali metal re-distribution after oxidation of 4H-SiC. In: 16th International Conference on Silicon Carbide and Related Materials, ICSCRM 2015: . Paper presented at 4 October 2015 through 9 October 2015 (pp. 677-680). Trans Tech Publications Ltd
Open this publication in new window or tab >>Alkali metal re-distribution after oxidation of 4H-SiC
2016 (English)In: 16th International Conference on Silicon Carbide and Related Materials, ICSCRM 2015, Trans Tech Publications Ltd , 2016, p. 677-680Conference paper, Published paper (Refereed)
Abstract [en]

Relocation of alkali metals sodium, potassium and cesium during oxidation of 4H-SiC has been studied by secondary ion mass spectrometry. The alkali metal source has been introduced by ion implantation before oxidation into n- and p-type 4H-SiC samples. Dry oxidation of SiC has been performed at 1150 ºC during 4, 8 and 16 h. In the formed oxide, the main part of the alkali metals diffuses out via the SiO2 surface. Close to the moving SiO2/SiC interface, a minor amount of alkali metals is retained. In the SiC material, the main amount of implanted alkali atoms is not redistributed during the oxidation, although a minor amount diffuses deeper into the samples. For ptype 4H-SiC, the diffusion deeper into the samples of the studied alkali metals decreases as the mass increases, Na+&lt;K+&lt;Cs+, but the sodium mobility is substantial already at 1150 °C.

Place, publisher, year, edition, pages
Trans Tech Publications Ltd, 2016
Keywords
Cesium, Diffusion, Oxidation, Potassium, SIMS, Sodium, Ion implantation, Mass spectrometry, Metals, Secondary ion mass spectrometry, Silicon oxides, Alkali atoms, Dry oxidation, Mass increase, P-type 4H-SiC, Re-distribution, SiC materials, Silicon carbide
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-195473 (URN)10.4028/www.scientific.net/MSF.858.677 (DOI)2-s2.0-84971570725 (Scopus ID)9783035710427 (ISBN)
Conference
4 October 2015 through 9 October 2015
Note

QC 20161125

Available from: 2016-11-25 Created: 2016-11-03 Last updated: 2016-11-25Bibliographically approved
Syväjärvi, M., Ma, Q., Jokubavicius, V., Galeckas, A., Sun, J., Liu, X., . . . Svensson, B. G. (2016). Cubic silicon carbide as a potential photovoltaic material. Solar Energy Materials and Solar Cells, 145, 104-108
Open this publication in new window or tab >>Cubic silicon carbide as a potential photovoltaic material
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2016 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 145, p. 104-108Article in journal (Refereed) Published
Abstract [en]

In this work we present a significant advancement in cubic silicon carbide (3C-SiC) growth in terms of crystal quality and domain size, and indicate its potential use in photovoltaics. To date, the use of 3C-SiC for photovoltaics has not been considered due to the band gap of 2.3 eV being too large for conventional solar cells. Doping of 3C-SiC with boron introduces an energy level of 0.7 eV above the valence band. Such energy level may form an intermediate band (IB) in the band gap. This IB concept has been presented in the literature to act as an energy ladder that allows absorption of sub-bandgap photons to generate extra electron-hole pairs and increase the efficiency of a solar cell. The main challenge with this concept is to find a materials system that could realize such efficient photovoltaic behavior. The 3C-SiC bandgap and boron energy level fits nicely into the concept, but has not been explored for an IB behavior. For a long time crystalline 3C-SiC has been challenging to grow due to its metastable nature. The material mainly consists of a large number of small domains if the 3C polytype is maintained. In our work a crystal growth process was realized by a new approach that is a combination of initial nucleation and step-flow growth. In the process, the domains that form initially extend laterally to make larger 3C-SiC domains, thus leading to a pronounced improvement in crystalline quality of 3C-SiC. In order to explore the feasibility of IB in 3C-SiC using boron, we have explored two routes of introducing boron impurities; ion implantation on un-doped samples and epitaxial growth on un-doped samples using pre-doped source material. The results show that 3C-SiC doped with boron is an optically active material, and thus is interesting to be further studied for IB behavior. For the ion implanted samples the crystal quality was maintained even after high implantation doses and subsequent annealing. The same was true for the samples grown with pre-doped source material, even with a high concentration of boron impurities. We present optical emission and absorption properties of as-grown and boron implanted 3C-SiC. The low-temperature photoluminescence spectra indicate the formation of optically active deep boron centers, which may be utilized for achieving an IB behavior at sufficiently high dopant concentrations. We also discuss the potential of boron doped 3C-SiC base material in a broader range of applications, such as in photovoltaics, biomarkers and hydrogen generation by splitting water.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
3C-SiC, Boron, Cubic, Doping, Intermediate band, Photovoltaic, Silicon carbide, Solar cell
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-180942 (URN)10.1016/j.solmat.2015.08.029 (DOI)000367772200004 ()2-s2.0-84949728460 (Scopus ID)
Funder
VINNOVASwedish Energy Agency
Note

QC 20160126. QC 20160205

Available from: 2016-01-26 Created: 2016-01-25 Last updated: 2017-11-30Bibliographically approved
Hallén, A. & Linnarsson, M. K. (2016). Ion implantation technology for silicon carbide. Paper presented at 19th International Conference on Surface Modification of Materials by Ion Beams (SMMIB), NOV 22-27, 2015, Chiang Mai, THAILAND. Surface & Coatings Technology, 306, 190-193
Open this publication in new window or tab >>Ion implantation technology for silicon carbide
2016 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 306, p. 190-193Article in journal (Refereed) Published
Abstract [en]

Ion implantation is a key process technique for semiconductor materials, in particular silicon, for local tailoring of the semiconductor properties. The wide bandgap semiconductor silicon carbide (SiC) features outstanding material properties for high power and high temperature electronic devices, but the properties of SiC also make it difficult to manufacture and process the material. The development of implantation technology for SiC has therefore necessitated several changes, from mainstream silicon implantation technology. This paper will discuss the difficulties with implantation of SiC for manufacturing of electronic devices and also describe how the problems have been overcome, for instance by implantation at elevated temperatures and using high temperature post-implant annealing. (C) 2016 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
SiC, Doping, Implantation damage, Diffusion, Activation, Annealing
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-197767 (URN)10.1016/j.surfcoat.2016.05.075 (DOI)000387526200037 ()2-s2.0-84971621270 (Scopus ID)
Conference
19th International Conference on Surface Modification of Materials by Ion Beams (SMMIB), NOV 22-27, 2015, Chiang Mai, THAILAND
Note

QC 20161229

Available from: 2016-12-29 Created: 2016-12-08 Last updated: 2017-11-29Bibliographically approved
Suvanam, S. S., Gulbinas, K., Usman, M., Linnarsson, M., Martin, D. M., Linnros, J., . . . Hallén, A. (2015). 4H-silicon carbide-dielectric interface recombination analysis using free carrier absorption. Journal of Applied Physics, 117(10), Article ID 105309.
Open this publication in new window or tab >>4H-silicon carbide-dielectric interface recombination analysis using free carrier absorption
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2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, no 10, article id 105309Article in journal (Refereed) Published
Abstract [en]

In this paper, an alternative method to characterize the interface between 4H polytype of Silicon Carbide (4H-SiC) and passivating dielectric layers is established. The studies are made on dielectric-semiconductor test structures using Al2O3 as dielectric on 4H-SiC n-type epitaxial layers. Samples with different pre-and post-dielectric deposition preparations have been fabricated on epilayers of varying thicknesses. Effective lifetimes (tau(eff)) of all the samples were measured by an optical pump-probe method utilizing free carrier absorption (FCA) to analyse the influence of the 4H-SiC/dielectric interface on charge carrier recombination. The relative contribution to tau(eff) from the surfaces increases with decreasing epilayer thickness, and by analysing the data in combination with numerical modelling, it is possible to extract values of the surface recombination velocities (SRVs) for interfaces prepared in different ways. For instance, it is found that SRV for a standard cleaning procedure is 2 x 10(6) cm/s compared to a more elaborate RCA process, yielding a more than 50 times lower value of 3.5 x 10(4) cm/s. Furthermore, the density of interface traps (D-it) is extracted from capacitance-voltage (CV) measurements using the Terman method and a comparison is made between the SRV extracted from FCA measurements and D(it)s extracted from CV measurements on the same structures fabricated with metal contacts. It is observed that the SRV increase scales linearly with the increase in Dit. The strong qualitative correlation between FCA and CV data shows that FCA is a useful characterization technique, which can also yield more quantitative information about the charge carrier dynamics at the interface.

National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-164450 (URN)10.1063/1.4914521 (DOI)000351442900065 ()2-s2.0-84924859308 (Scopus ID)
Note

QC 20150423

Available from: 2015-04-23 Created: 2015-04-17 Last updated: 2017-12-04Bibliographically approved
Ou, H., Ou, Y., Argyraki, A., Schimmel, S., Kaiser, M., Wellmann, P., . . . Syväjärvi, M. (2014). Advances in wide bandgap SiC for optoelectronics. European Physical Journal B: Condensed Matter Physics, 87(3), 58
Open this publication in new window or tab >>Advances in wide bandgap SiC for optoelectronics
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2014 (English)In: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 87, no 3, p. 58-Article in journal (Refereed) Published
Abstract [en]

Silicon carbide (SiC) has played a key role in power electronics thanks to its unique physical properties like wide bandgap, high breakdown field, etc. During the past decade, SiC is also becoming more and more active in optoelectronics thanks to the progress in materials growth and nanofabrication. This paper will review the advances in fluorescent SiC for white light-emitting diodes, covering the polycrystalline doped SiC source material growth, single crystalline epitaxy growth of fluorescent SiC, and nanofabrication of SiC to enhance the extraction efficiency for fluorescent SiC based white LEDs.

Keywords
Chemical-Vapor-Deposition, Antireflective Subwavelength Structures, Sublimation Sandwich Method, Silicon-Carbide Surface, Acceptor-Pair Emission, Light-Emitting Diode, Epitaxial-Growth, Broad-Band, Layers, Transport
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-144118 (URN)10.1140/epjb/e2014-41100-0 (DOI)000332697900001 ()2-s2.0-84897810808 (Scopus ID)
Funder
Swedish Energy AgencySwedish Research Council, 2009-5307
Note

QC 20140414

Available from: 2014-04-14 Created: 2014-04-10 Last updated: 2017-12-05Bibliographically approved
Grivickas, V., Gulbinas, K., Jokubaviius, V., Sun, J. W., Karalinas, M., Kamiyama, S., . . . Syväjärvi, M. (2014). Carrier lifetimes and influence of in-grown defects in N-B Co-doped 6H-SiC. In: IOP Conference Series: Materials Science and Engineering. Paper presented at Symposium G on Alternative Approaches of SiC and Related Wide Bandgap Materials in Light Emitting and Solar Cell Applications, Held at the EMRS 2013 Spring Meeting, 27 May 2013 through 31 May 2013, Strasbourg. , 56(1)
Open this publication in new window or tab >>Carrier lifetimes and influence of in-grown defects in N-B Co-doped 6H-SiC
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2014 (English)In: IOP Conference Series: Materials Science and Engineering, 2014, Vol. 56, no 1Conference paper, Published paper (Refereed)
Abstract [en]

The thick N-B co-doped epilayers were grown by the fast sublimation growth method and the depth-resolved carrier lifetimes have been investigated by means of the free-carrier absorption (FCA) decay under perpendicular probe-pump measurement geometry. In some samples, we optically reveal in-grown carbon inclusions and polycrystalline defects of substantial concentration and show that these defects slow down excess carrier lifetime and prevent donor-acceptor pair photo luminescence (DAP PL). A pronounced electron lifetime reduction when injection level approaches the doping level was observed. It is caused by diffusion driven non-radiative recombination. However, the influence of surface recombination is small and insignificant at 300 K.

Series
IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981 ; 012004
Keywords
Energy gap, Light emission, Silicon carbide, Solar cells, Diffusion driven, Donor-acceptor pairs, Electron lifetime, Free carrier absorption, Measurement geometry, Non-radiative recombinations, Sublimation growth, Surface recombinations, Carrier lifetime
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-167561 (URN)10.1088/1757-899X/56/1/012004 (DOI)000338125900004 ()2-s2.0-84902209266 (Scopus ID)
Conference
Symposium G on Alternative Approaches of SiC and Related Wide Bandgap Materials in Light Emitting and Solar Cell Applications, Held at the EMRS 2013 Spring Meeting, 27 May 2013 through 31 May 2013, Strasbourg
Note

QC 20150602

Available from: 2015-06-02 Created: 2015-05-22 Last updated: 2015-06-02Bibliographically approved
Linnarsson, M. & Hallén, A. (2014). Diffusion of alkali metals in SiC. In: Silicon Carbide and Related Materials 2013, PTS 1 and 2: . Paper presented at 15th International Conference on Silicon Carbide and Related Materials (ICSCRM 2013), SEP 29-OCT 04, 2013, Miyazaki, JAPAN (pp. 297-300).
Open this publication in new window or tab >>Diffusion of alkali metals in SiC
2014 (English)In: Silicon Carbide and Related Materials 2013, PTS 1 and 2, 2014, p. 297-300Conference paper, Published paper (Refereed)
Abstract [en]

Diffusion of lithium, sodium and potassium in SiC has been studied by secondary ion mass spectrometry. The alkali metal diffusion sources have been introduced by ion implantation. Subsequent anneals have been carried out in vacuum or in Ar atmosphere in the temperature range 700 degrees C - 1500 degrees C for 5 min to 16 h. The bombardment-induced defects in the vicinity of the ion implanted profile are readily decorated by the implanted. In the bulk, the diffusing alkali metals are most likely trapped and detrapped at boron and/or other defects during diffusion. The diffusivity of the studied alkali metals decreases as the mass increases, Li+<Na+<K+, but the sodium mobility in SiC is substantial already at 1100 degrees C.

Series
Materials Science Forum, ISSN 0255-5476 ; 778-780
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-147443 (URN)10.4028/www.scientific.net/MSF.778-780.297 (DOI)000336634100070 ()2-s2.0-84896068123 (Scopus ID)
Conference
15th International Conference on Silicon Carbide and Related Materials (ICSCRM 2013), SEP 29-OCT 04, 2013, Miyazaki, JAPAN
Note

QC 20140627

Available from: 2014-06-27 Created: 2014-06-27 Last updated: 2015-02-20Bibliographically approved
Kobayashi, T., Primetzhofer, D., Linnarsson, M. & Hallén, A. (2014). Ion-stimulated desorption in the medium-energy regime. Japanese Journal of Applied Physics, 53(6), 060305
Open this publication in new window or tab >>Ion-stimulated desorption in the medium-energy regime
2014 (English)In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 53, no 6, p. 060305-Article in journal (Refereed) Published
Abstract [en]

Ion-stimulated desorption in the medium-energy regime is investigated using a hydrogen rich Li2O sample. The desorbed yield dependencies for H+ and Li+ on incident ion species H-1(+) and He-4(+) in a medium energy regime are measured. For the mechanism of desorption it is considered that an inner shell electron vacancy is generated in oxygen atoms of the target by the ion impact. This inner shell vacant state is then filled by Auger transition of an electron from surrounding H or Li atoms. The resulting coulomb repulsion between H+ or Li+ and O+ leads to ejection of H+ or Li+ from the surface.

Keywords
Scattering, Interface
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-148313 (URN)10.7567/JJAP.53.060305 (DOI)000338104600006 ()2-s2.0-84903124540 (Scopus ID)
Note

QC 20140808

Available from: 2014-08-08 Created: 2014-08-05 Last updated: 2017-12-05Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0292-224X

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