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Publications (10 of 206) Show all publications
Suvanam, S. S., Larsen, J., Ross, N., Kosyak, V., Hallén, A. & Björkman, C. P. (2018). Extreme radiation hard thin film CZTSSe solar cell. Solar Energy Materials and Solar Cells, 185, 16-20
Open this publication in new window or tab >>Extreme radiation hard thin film CZTSSe solar cell
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2018 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 185, p. 16-20Article in journal (Refereed) Published
Abstract [en]

In this work, we have demonstrated the extreme radiation hardness of thin film CZTSSe solar cells. Thin film solar cells with CZTSSe, CZTS and CIGS absorber layers were irradiated with 3 MeV protons. No degradation in device parameters was observed until a displacement damage dose of 2 × 1010 MeV/g for CZTS and CZTSSe. CIGS solar cells degraded by 13% at the same dose. For the highest proton dose both the CZTSSe and CZTS degraded by 16% while CIGS suffered from 34% degradation in efficiency. The degradation in efficiency maybe attributed to the reduction in the minority carrier lifetime due to radiation induced lattice defects. Comparisons with previously available literature show that our CZTS technology has superior radiation hardness by about two orders of magnitude compared to existing state of the art Si and GaAs technology.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
CZTSSe, Proton radiation, Radiation hardness, Space solar cells
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:kth:diva-228694 (URN)10.1016/j.solmat.2018.05.012 (DOI)000437816100003 ()2-s2.0-85046621751 (Scopus ID)
Note

QC 20180530

Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-07-27Bibliographically approved
Chulapakorn, T., Primetzhofer, D., Sychugov, I., Suvanam, S. S., Linnros, J. & Hallén, A. (2018). Impact of H-uptake by forming gas annealing and ion implantation on photoluminescence of Si-nanoparticles. Physica Status Solidi (a) applications and materials science, 215(3), Article ID 1700444.
Open this publication in new window or tab >>Impact of H-uptake by forming gas annealing and ion implantation on photoluminescence of Si-nanoparticles
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2018 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 215, no 3, article id 1700444Article in journal (Refereed) Published
Abstract [en]

Silicon nanoparticles (SiNPs) are formed by implanting 70 keV Si+ into a SiO2-film and subsequent thermal annealing. SiNP samples are further annealed in forming gas. Another group of samples containing SiNP is implanted by 7.5 keV H+ and subsequently annealed in N2-atmosphere at 450 °C to reduce implantation damage. Nuclear reaction analysis (NRA) is employed to establish depth profiles of the H-concentration. Enhanced hydrogen concentrations are found close to the SiO2surface, with particularly high concentrations for the as-implanted SiO2. However, no detectable uptake of hydrogen is observed by NRA for samples treated by forming gas annealing (FGA). H-concentrations detected after H-implantation follow calculated implantation profiles. Photoluminescence (PL) spectroscopy is performed at room temperature to observe the SiNP PL. Whereas FGA is found to increase PL under certain conditions, i.e., annealing at high temperatures, increasing implantation fluence of H reduces the SiNP PL. Hydrogen implantation also introduces additional defect PL. After low-temperature annealing, the SiNP PL is found to improve, but the process is not found equivalently efficient as conventional FGA.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
H-quantification, nuclear reaction analysis, photoluminescence, silicon nanoparticles
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-219544 (URN)10.1002/pssa.201700444 (DOI)000424387300006 ()2-s2.0-85031427795 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20171219

Available from: 2017-12-17 Created: 2017-12-17 Last updated: 2018-02-22Bibliographically approved
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
Ayedh, H. M., Nipoti, R., Hallén, A. & Svensson, B. G. (2018). Kinetics modeling of the carbon vacancy thermal equilibration in 4H-SiC. In: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017: . Paper presented at 17 September 2017 through 22 September 2017 (pp. 233-236). Trans Tech Publications
Open this publication in new window or tab >>Kinetics modeling of the carbon vacancy thermal equilibration in 4H-SiC
2018 (English)In: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017, Trans Tech Publications, 2018, p. 233-236Conference paper, Published paper (Refereed)
Abstract [en]

The carbon vacancy (VC) is a major limiting-defect of minority carrier lifetime in n-type 4H-SiC epitaxial layers and it is readily formed during high temperature processing. In this study, a kinetics model is put forward to address the thermodynamic equilibration of VC, elucidating the possible atomistic mechanisms that control the VC equilibration under C-rich conditions. Frenkel pair generation, injection of carbon interstitials (Ci’s) from the C-rich surface, followed by recombination with VC’s, and diffusion of VC’s towards the surface appear to be the major mechanisms involved. The modelling results show a close agreement with experimental deep-level transient spectroscopy (DLTS) depth profiles of VC after annealing at different temperatures.

Place, publisher, year, edition, pages
Trans Tech Publications, 2018
Keywords
4H-SiC, Carbon vacancy, Diffusion, Kinetics model, Thermodynamic equilibrium, Carbon, Carrier lifetime, Deep level transient spectroscopy, Kinetics, Atomistic mechanism, High-temperature processing, Kinetics modeling, Minority carrier lifetimes, Thermal equilibrations, Thermodynamic equilibria, Silicon carbide
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-236387 (URN)10.4028/www.scientific.net/MSF.924.233 (DOI)2-s2.0-85049002040 (Scopus ID)9783035711455 (ISBN)
Conference
17 September 2017 through 22 September 2017
Note

QC 20181101

Available from: 2018-11-01 Created: 2018-11-01 Last updated: 2018-11-01Bibliographically approved
Chulapakorn, T., Sychugov, I., Ottosson, M., Primetzhofer, D., Moro, M. V., Linnros, J. & Hallén, A. (2018). Luminescence of silicon nanoparticles from oxygen implanted silicon. Materials Science in Semiconductor Processing, 86, 18-22
Open this publication in new window or tab >>Luminescence of silicon nanoparticles from oxygen implanted silicon
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2018 (English)In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 86, p. 18-22Article in journal (Refereed) Published
Abstract [en]

Oxygen with a kinetic energy of 20 keV is implanted in a silicon wafer (100) at different fluences, followed by post-implantation thermal annealing (PIA) performed at temperatures ranging from 1000 to 1200 degrees C, in order to form luminescent silicon nanoparticles (SiNPs) and also to reduce the damage induced by the implantation. As a result of this procedure, a surface SiOx layer (with 0 < x < 2) with embedded crystalline Si nanoparticles has been created. The samples yield similar luminescence in terms of peak wavelength, lifetime, and absorption as recorded from SiNPs obtained by the more conventional method of implanting silicon into silicon dioxide. The oxygen implantation profile is characterized by elastic recoil detection (ERD) technique to obtain the excess concentration of Si in a presumed SiO2 environment. The physical structure of the implanted Si wafer is examined by grazing incidence X-ray diffraction (GIXRD). Photoluminescence (PL) techniques, including PL spectroscopy, time-resolved PL (TRPL), and photoluminescence excitation (PLE) spectroscopy are carried out in order to identify the PL origin. The results show that luminescent SiNPs are formed in a Si sample implanted by oxygen with a fluence of 2 x 10(17) atoms cm(-2) and PIA at 1000 degrees C. These SiNPs have a broad size range of 6-24 nm, as evaluated from the GIXRD result. Samples implanted at a lower fluence and/or annealed at higher temperature show only weak defect-related PL. With further optimization of the SiNP luminescence, the method may offer a simple route for integration of luminescent Si in mainstream semiconductor fabrication.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Oxygen implantation, Silicon nanoparticles, Photoluminescence
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-232741 (URN)10.1016/j.mssp.2018.06.004 (DOI)000439119400003 ()2-s2.0-85048803830 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , RIF14-0053Swedish Research Council, 821-2012-5144 2017-00646_9 821-2012-5144 2017-00646_9
Note

QC 20180803

Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2018-08-06Bibliographically approved
Hallén, A. & Suvanam, S. S. (2018). Radiation hardness for silicon oxide and aluminum oxide on 4H-SiC. In: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017: . Paper presented at International Conference on Silicon Carbide and Related Materials, ICSCRM 2017, Columbia, United States, 17 September 2017 through 22 September 2017 (pp. 229-232). Trans Tech Publications Inc., 924
Open this publication in new window or tab >>Radiation hardness for silicon oxide and aluminum oxide on 4H-SiC
2018 (English)In: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017, Trans Tech Publications Inc., 2018, Vol. 924, p. 229-232Conference paper, Published paper (Refereed)
Abstract [en]

The radiation hardness of two dielectrics, SiO2 and Al2O3, deposited on low doped, ntype 4H-SiC epitaxial layers has been investigated by exposing MOS structures involving these materials to MeV proton irradiation. The samples are examined by capacitance voltage (CV) measurements and, from the flat band voltage shift, it is concluded that positive charge is induced in the exposed structures detectable for fluence above 1×1011 cm-2. The positive charge increases with proton fluence, but the SiO2/4H-SiC structures are slightly more sensitive, showing that Al2O3 can provide a more radiation hard passivation, or gate dielectric for 4H-SiC devices.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2018
Series
Materials Science Forum, ISSN 0255-5476 ; 924
Keywords
Capacitance, Charge, Dielectric, Flat band voltage, Irradiation, Protons
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-238397 (URN)10.4028/www.scientific.net/MSF.924.229 (DOI)2-s2.0-85049034444 (Scopus ID)9783035711455 (ISBN)
Conference
International Conference on Silicon Carbide and Related Materials, ICSCRM 2017, Columbia, United States, 17 September 2017 through 22 September 2017
Note

QC 20181108

Available from: 2018-11-08 Created: 2018-11-08 Last updated: 2018-11-08Bibliographically approved
Linnarsson, M. K., Ayedh, H. M., Hallén, A., Vines, L. & Svensson, B. G. (2018). Surface erosion of ion-implanted 4H-SiC during annealing with carbon cap. In: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017: . Paper presented at International Conference on Silicon Carbide and Related Materials, ICSCRM 2017; Columbia; United States; 17 September 2017 through 22 September 2017 (pp. 373-376). Trans Tech Publications Inc., 924
Open this publication in new window or tab >>Surface erosion of ion-implanted 4H-SiC during annealing with carbon cap
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2018 (English)In: International Conference on Silicon Carbide and Related Materials, ICSCRM 2017, Trans Tech Publications Inc., 2018, Vol. 924, p. 373-376Conference paper, Published paper (Refereed)
Abstract [en]

The stability/ erosion of the interface between a C-cap and 4H-SiC have been studied by secondary ion mass spectrometry (SIMS). Aluminum implantation has been used to monitor the position of the moving interface as well as to investigate the influence on the interface stability by the crystal quality of the 4H-SiC. After Al implantation a C-cap has been deposited by pyrolysis of photoresist. Subsequent annealing has been performed at 1900 and 2000 °C with durations between 15 minutes and 1 hour. SIMS measurements have been performed without removal of the C-cap. The surface remains smooth after the heat treatment, but a large amount of SiC material from the uppermost part of the wafer is lost. The amount of lost material is related to for instance annealing temperature, ambient conditions and ion induced crystal damage. This contribution gives a brief account of the processes governing the SiC surface decomposition during C-cap post implant annealing.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2018
Series
Materials Science Forum, ISSN 0255-5476 ; 924
Keywords
Annealing, Carbon-cap, SIMS
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-238421 (URN)10.4028/www.scientific.net/MSF.924.373 (DOI)2-s2.0-85049021647 (Scopus ID)9783035711455 (ISBN)
Conference
International Conference on Silicon Carbide and Related Materials, ICSCRM 2017; Columbia; United States; 17 September 2017 through 22 September 2017
Note

QC 20181107

Available from: 2018-11-07 Created: 2018-11-07 Last updated: 2018-11-07Bibliographically approved
Azarov, A., Rauwel, P., Hallén, A., Monakhov, E. & Svensson, B. G. (2017). Extended defects in ZnO: Efficient sinks for point defects. Applied Physics Letters, 110(2), Article ID 022103.
Open this publication in new window or tab >>Extended defects in ZnO: Efficient sinks for point defects
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2017 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 110, no 2, article id 022103Article in journal (Refereed) Published
Abstract [en]

Dopant-defect reactions dominate the defect formation in mono-crystalline ZnO samples implanted with Ag and B ions. This is in contrast to most other ion species studied and results in an enhanced concentration of extended defects, such as stacking faults and defect clusters. Using a combination of B and Ag implants and diffusion of residual Li atoms as a tracer, we demonstrate that extended defects in ZnO act as efficient traps for highly mobile Zn interstitials. The results imply that dynamic annealing involving interaction of point defects with extended ones can play a key role in the disorder saturation observed for ZnO and other radiation-hard semiconductors implanted with high doses.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-202434 (URN)10.1063/1.4973463 (DOI)000392835300033 ()2-s2.0-85009191857 (Scopus ID)
Note

QC 20170306

Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-11-29Bibliographically approved
Chulapakorn, T., Sychugov, I., Suvanam, S. S., Linnros, J., Primetzhofer, D. & Hallén, A. (2017). Influence of swift heavy ion irradiation on the photoluminescence of Si-nanoparticles and defects in SiO2. Nanotechnology, 28, Article ID 375606.
Open this publication in new window or tab >>Influence of swift heavy ion irradiation on the photoluminescence of Si-nanoparticles and defects in SiO2
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2017 (English)In: Nanotechnology, Vol. 28, article id 375606Article in journal (Refereed) Published
Abstract [en]

The influence of swift heavy ion (SHI) irradiation on the photoluminescence (PL) of silicon nanoparticles (SiNPs) and defects in SiO2-film is investigated. SiNPs were formed by implantation of 70 keV Si+ and subsequent thermal annealing to produce optically active SiNPs and to remove implantation-induced defects. Seven different ion species with energy between 3-36 MeV and fluence from 10(11)-10(14) cm(-2) were employed for irradiation of the implanted samples prior to the thermal annealing. Induced changes in defect and SiNP PL were characterized and correlated with the specific energy loss of the employed SHIs. We find that SHI irradiation, performed before the thermal annealing process, affects both defect and SiNP PL. The change of defect and SiNP PL due to SHI irradiation is found to show a threshold-like behaviour with respect to the electronic stopping power, where a decrease in defect PL and an anticorrelated increase in SiNP PL after the subsequent thermal annealing are observed for electronic stopping exceeding 3-5 keV nm(-1). PL intensities are also compared as a function of total energy deposition and nuclear energy loss. The observed effects can be explained by ion track formation as well as a different type of annealing mechanisms active for SHI irradiation compared to the thermal annealing.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2017
Keywords
silicon nanoparticle; ion implantation; photoluminescence; swift heavy ion irradiation
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-219545 (URN)10.1088/1361-6528/aa824f (DOI)000408244000002 ()2-s2.0-85028462224 (Scopus ID)
Note

QC 20171219

Available from: 2017-12-17 Created: 2017-12-17 Last updated: 2017-12-19Bibliographically 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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8760-1137

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