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Suvanam, Sethu Saveda
Publications (7 of 7) Show all publications
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
Usman, M., Suvanam, S. S., Linnarsson, M. & Hallén, A. (2018). Improving the quality of Al2O3/4H-SiC interface for device applications. Materials Science in Semiconductor Processing, 81, 118-121
Open this publication in new window or tab >>Improving the quality of Al2O3/4H-SiC interface for device applications
2018 (English)In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 81, p. 118-121Article in journal (Refereed) Published
Abstract [en]

The present paper focuses on the investigation of Al2O3/4H-SiC dielectric interface upon annealing, its consequent structural modifications, and the link to electrical properties. For this purpose, the test structures are prepared by depositing Al2O3, using atomic layer deposition (ALD), on low doped n-type 4H-SiC epitaxial layers. The structures are annealed from 300 degrees C to 1100 degrees C for different time duration (from 5 to 60 mins) and ambient such as, low vacuum (10(-1) Torr), N-2, and N2O. The structural studies on these samples are conducted using synchrotron-based high resolution x-ray photoelectron spectroscopy (HR-XPS), lab-based XPS, time of flight elastic recoil detection analysis (ToF-ERDA), and time of flight medium energy ion scattering (ToF-MEIS). The electrical response of capacitive structures is monitored through capacitance voltage (CV) measurements for as-deposited and annealed structures. It is found that the annealing at high temperatures, such as 1100 degrees C, and in N-2 or N2O environment, improves the dielectric properties due to the introduction of a thin layer of about 1 nm stable SiO2 between the Al2O3 and 4H-SiC.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
4H-SiC, Al2O3, Dielectric interface, XPS, Annealing, MEIS
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-226731 (URN)10.1016/j.mssp.2018.02.036 (DOI)000429746200020 ()2-s2.0-85044116454 (Scopus ID)
Funder
Swedish Research Council, D0674701
Note

QC 20180502

Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2018-05-02Bibliographically approved
Usman, M., Arshad, M., Suvanam, S. S. & Hallen, A. (2018). Influence of annealing environment on the ALD-Al2O3/4H-SiC interface studied through XPS. Journal of Physics D: Applied Physics, 51(10), Article ID 105111.
Open this publication in new window or tab >>Influence of annealing environment on the ALD-Al2O3/4H-SiC interface studied through XPS
2018 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 10, article id 105111Article in journal (Refereed) Published
Abstract [en]

The instability of Al2O3/4H-SiC interface at various process temperatures and ambient is investigated by the annealing of Al2O3/4H-SiC in low vacuum conditions as well as in N-2 environments. Atomic layer deposited Al2O3 on a 4H-SiC substrate with 3, 6 and 10 nm of thicknesses is treated at 300, 500, 700 and 900 degrees C under the vacuum level of 10(-1) torr. The as-deposited and annealed structures are analyzed using x-ray photoelectron spectroscopy. It is hypothesized that the minute quantity of oxygen present in low vacuum conditions diffuses through thin layers of Al2O3 and helps in forming SiO2 at the interface even at low temperatures (i.e. 300 degrees C), which plays a pivotal role in determining the electrical properties of the interface. It is also proved that the absence of oxygen in the ambient prevents the formation of SiO2 at low temperatures. Additionally, it is observed that Al-OH is present in as-deposited layers, which gradually reduces after annealing. However, at around 700 degrees C, the concentration of oxygen in the whole structure increases to maximum and reduces at 900 degrees C.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
Al2O3/4H-SiC interface, oxygen diffusion, annealing, XPS
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-224005 (URN)10.1088/1361-6463/aaa9a1 (DOI)000425627200003 ()2-s2.0-85042358184 (Scopus ID)
Note

QC 20180319

Available from: 2018-03-19 Created: 2018-03-19 Last updated: 2018-03-19Bibliographically approved
Suvanam, S. S., Lanni, L., Malm, B. G., Zetterling, C.-M. & Hallén, A. (2017). Total Dose Effects on 4H-SiC Bipolar Junction Transistors. In: : . Paper presented at European Conference on Silicon Carbide and Related Materials 2016 (ECSCRM-16). Material science Forum
Open this publication in new window or tab >>Total Dose Effects on 4H-SiC Bipolar Junction Transistors
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2017 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Material science Forum, 2017
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-199903 (URN)10.4028/www.scientific.net/MSF.897.579 (DOI)2-s2.0-85020007905 (Scopus ID)
Conference
European Conference on Silicon Carbide and Related Materials 2016 (ECSCRM-16)
Note

QC 20170201

Available from: 2017-01-17 Created: 2017-01-17 Last updated: 2017-10-23Bibliographically 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+<K+<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
Chulapakorn, T., Sychugov, I., Suvanam, S. S., Linnros, J. T., Primetzhofer, D. & Hallén, A. (2016). MeV ion irradiation effects on the luminescence properties of Si-implanted SiO2-thin films. Physica Status Solidi (C) Current Topics in Solid State Physics, 13(10-12), 921-926
Open this publication in new window or tab >>MeV ion irradiation effects on the luminescence properties of Si-implanted SiO2-thin films
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2016 (English)In: Physica Status Solidi (C) Current Topics in Solid State Physics, ISSN 1862-6351, Vol. 13, no 10-12, p. 921-926Article in journal (Refereed) Published
Abstract [en]

The effects of MeV heavy ion irradiation at varying fluence and flux on excess Si, introduced in SiO2 by keV ion implantation, are investigated by photoluminescence (PL). From the PL peak wavelength (λ) and decay lifetime (τ), two PL sources are distinguished: i) quasi-direct recombination of excitons of Si-nanoparticles (SiNPs), appearing after thermal annealing (λ > 720 nm, τ ∼ μs), and ii) fast-decay PL, possibly due to oxide-related defects (λ ∼ 575-690 nm, τ ∼ ns). The fast-decay PL (ii) observed before and after ion irradiation is induced by ion implantation. It is found that this fast-decay luminescence decreases for higher irradiation fluence of MeV heavy ions. After thermal annealing (forming SiNPs), the SiNP PL is reduced for samples irradiated by MeV heavy ions but found to stabilize at higher level for higher irradiation flux; the (ii) band vanishes as a result of annealing. The results are discussed in terms of the influence of electronic and nuclear stopping powers.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2016
Keywords
ion implantation, MeV heavy ion irradiation, photoluminescence, silicon nanoparticle, Annealing, Ion bombardment, Irradiation, Luminescence, Nanoparticles, Radiation, Silicon, Silicon oxides, Direct recombination, KeV ion implantation, Luminescence properties, MeV ion irradiation, Nuclear stopping, Si nanoparticles, Silicon nanoparticles, Thermal-annealing, Heavy ions
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-201925 (URN)10.1002/pssc.201600077 (DOI)000399448900040 ()2-s2.0-84992456246 (Scopus ID)
Note

QC 20170302

Available from: 2017-03-02 Created: 2017-03-02 Last updated: 2017-06-02Bibliographically approved
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