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Azarov, A., Galeckas, A., Mieszczyński, C., Hallén, A. & Kuznetsov, A. (2020). Effects of annealing on photoluminescence and defect interplay in ZnO bombarded by heavy ions: Crucial role of the ion dose. Journal of Applied Physics, 127(2), Article ID 025701.
Open this publication in new window or tab >>Effects of annealing on photoluminescence and defect interplay in ZnO bombarded by heavy ions: Crucial role of the ion dose
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2020 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 127, no 2, article id 025701Article in journal (Refereed) Published
Abstract [en]

Bombardment of ZnO with heavy ions generating dense collision cascades is of particular interest because of the formation of nontrivial damage distribution involving a defected layer located between the surface and the bulk damage regions, as seen by Rutherford backscattering spectroscopy in the channeling mode. By correlating photoluminescence and channeling data, we demonstrate that the thermal evolution of defects in wurtzite ZnO single crystals implanted with Cd ions strongly depends on the implanted dose. Specifically, the ion dose has a profound effect on the optical response in the spectral range between the near-band-edge emission and deep-level emission bands. The interplay between interstitial and vacancy type defects during annealing is discussed in relation to the evolution of the multipeak damage distribution.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2020
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-267831 (URN)10.1063/1.5134011 (DOI)000515676400037 ()2-s2.0-85077965168 (Scopus ID)
Note

QC 20200306

Available from: 2020-03-06 Created: 2020-03-06 Last updated: 2020-03-16Bibliographically approved
Tian, K., Hallén, A., Qi, J., Ma, S., Fei, X., Zhang, A. & Liu, W. (2019). An Improved 4H-SiC Trench-Gate MOSFET With Low ON-Resistance and Switching Loss. IEEE Transactions on Electron Devices, 66(5), 2307-2313, Article ID 8681267.
Open this publication in new window or tab >>An Improved 4H-SiC Trench-Gate MOSFET With Low ON-Resistance and Switching Loss
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2019 (English)In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 66, no 5, p. 2307-2313, article id 8681267Article in journal (Refereed) Published
Abstract [en]

In this paper, an improved 4H-SiC U-shaped trench-gate metal-oxide-semiconductor field-effect transistors (UMOSFETs) structure with low ON-resistance (R ON ) and switching energy loss is proposed. The novel structure features an added n-type region, which reduces ON-resistance of the device significantly while maintaining the breakdown voltage (V BR ). In addition, the gate of the improved structure is designed as a p-n junction to reduce the switching energy loss. Simulations by Sentaurus TCAD are carried out to reveal the working mechanism of this improved structure. For the static performance, the ON-resistance and the figure of merit (FOM = V BR 2 /R ON ) of the optimized structure are improved by 40% and 44%, respectively, as compared to a conventional trench MOSFET without the added n-type region and modified gate. For the dynamic performance, the turn-on time (T ON ) and turn-off time (T OFF ) of the proposed structure are both shorter than that of the conventional structure, bringing a 43% and 30% reduction in turn-on energy loss and total switching energy loss (E SW ). © 2019 IEEE.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Breakdown voltage, ON-resistance, silicon carbide, switching energy loss, U-shaped trench-gate metal-oxide-semiconductor field-effect transistors (UMOSFETs), Dielectric devices, Electric breakdown, Energy dissipation, Metallic compounds, Metals, MOS devices, Oxide semiconductors, Semiconducting silicon compounds, Semiconductor junctions, Switching, Transistors, Wide band gap semiconductors, Conventional structures, Dynamic performance, Improved structures, Optimized structures, Switching energy, Trench gates, Trench-gate mosfet, MOSFET devices
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-252507 (URN)10.1109/TED.2019.2905636 (DOI)000466028500041 ()2-s2.0-85064973294 (Scopus ID)
Note

QC 20190710

Available from: 2019-07-10 Created: 2019-07-10 Last updated: 2019-10-24Bibliographically approved
Linnarsson, M. K., Hallén, A., Vines, L. & Svensson, B. (2019). Channeling implantations of p-type dopants into 4H-SiC at different tempertures. Materials Science Forum, 963, 382-385
Open this publication in new window or tab >>Channeling implantations of p-type dopants into 4H-SiC at different tempertures
2019 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 963, p. 382-385Article in journal (Refereed) Published
Abstract [en]

Channeling of B and Al ions in 4H-SiC(0001), has been investigated by secondary ion mass spectrometry (SIMS). Ion implantations have been performed between room temperature (RT) and 600 °C at various fluences. Before implantation, the major crystal axes were determined and the sample was aligned using the blocking pattern of backscattered protons. As expected, the depth distribution of the implanted ions along a crystal direction penetrates much deeper compared to nonchanneling directions. At elevated temperatures, the channeling depth for 100 keV Al-ions is decreased due to lattice vibrations. For 50 keV B-ions, the temperature effect is minor, indicating a smaller interaction between target atoms and B. Simulations has been performed using SIIMPL, a Monte Carlo simulation code based on the binary collision approximation, to predict experimental data and get a deeper insight in the channeling process.

Place, publisher, year, edition, pages
Trans Tech Publications Ltd, 2019
Keywords
Aluminum; Boron; ChannelingIon implantation; SIMS
National Category
Natural Sciences Physical Sciences Condensed Matter Physics
Research subject
Physics, Material and Nano Physics
Identifiers
urn:nbn:se:kth:diva-264231 (URN)10.4028/www.scientific.net/MSF.963.382 (DOI)2-s2.0-85071863753 (Scopus ID)
Funder
Swedish Research Council, E0510501
Note

QC 20191210

Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2019-12-10Bibliographically approved
Tian, K., Hallén, A., Qi, J., Nawaz, M., Ma, S., Wang, M., . . . Liu, W. (2019). Comprehensive Characterization of the 4H-SiC Planar and Trench Gate MOSFETs From Cryogenic to High Temperature. IEEE Transactions on Electron Devices, 66(10), 4279-4286
Open this publication in new window or tab >>Comprehensive Characterization of the 4H-SiC Planar and Trench Gate MOSFETs From Cryogenic to High Temperature
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2019 (English)In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 66, no 10, p. 4279-4286Article in journal (Refereed) Published
Abstract [en]

In this article, the static, dynamic, and short-circuit properties of 1.2-kV commercial 4H-SiC planar and trench gate metal-oxide-semiconductor field-effect transistors (MOSFETs) are compared and analyzed in a wide temperature range from 90 to 493 K. The temperature-dependent specific ON-resistance (Rsp-ON) and threshold voltage (V-th) are analyzed in relation to the density of the interface state. The turn-on rise and turn-off fall times (T-r and T-f) and the corresponding energy loss (E-r and E-f) are extracted from a double-pulse test from cryogenic to high temperature and analyzed. The short-circuit capability of the two structures is studied at low temperature for the first time. The comprehensive comparison and analysis of the planar and trench gate MOSFET versus temperature in this work show the importance to study applications with SiC MOSFETs in a wide temperature range, especially for the cryogenic temperatures.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
ON-resistance, planar metal-oxide-semiconductor field-effect transistors (MOSFETs), short-circuit capability, silicon carbide, switching loss, switching time, temperature, threshold voltage, Trench MOSFETs
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-264300 (URN)10.1109/TED.2019.2934507 (DOI)000487477600025 ()2-s2.0-85077759893 (Scopus ID)
Note

QC 20191203

Available from: 2019-12-03 Created: 2019-12-03 Last updated: 2020-03-09Bibliographically approved
Azarov, A., Aarseth, B. L., Vines, L., Hallén, A., Monakhov, E. & Kuznetsov, A. (2019). Defect annealing kinetics in ZnO implanted with Zn substituting elements: Zn interstitials and Li redistribution. Journal of Applied Physics, 125(7), Article ID 075703.
Open this publication in new window or tab >>Defect annealing kinetics in ZnO implanted with Zn substituting elements: Zn interstitials and Li redistribution
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2019 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, no 7, article id 075703Article in journal (Refereed) Published
Abstract [en]

It is known that the behavior of residual Li in ion implanted ZnO depends on the preferential localization of the implants, in particular, forming characteristic Li depleted or Li pile-up regions for Zn or O sublattice occupation of the implants due to the corresponding excess generation of Zn and O interstitials in accordance with the so-called "+1 model." However, the present study reveals that conditions for the radiation damage annealing introduce additional complexity into the interpretation of the Li redistribution trends. Specifically, four implants residing predominantly in the Zn-sublattice, but exhibiting different lattice recovery routes, were considered. Analyzing Li redistribution trends in these samples, it is clearly shown that Li behavior depends on the defect annealing kinetics which is a strong function of the implanted fluence and ion species. Thus, Li depleted and Li pile-up regions (or even combinations of the two) were observed and correlated with the defect evolution in the samples. It is discussed how the observed Li redistribution trends can be used for better understanding a thermal evolution of point defects in ZnO and, in particular, energetics and migration properties of Zn interstitials.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-246261 (URN)10.1063/1.5083226 (DOI)000459401100033 ()2-s2.0-85061705252 (Scopus ID)
Note

QC 20190326

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-04-04Bibliographically approved
Majdi, S., Gabrysch, M., Suntornwipat, N., Burmeister, F., Jonsson, R., Kovi, K. K. & Hallén, A. (2019). High-temperature deep-level transient spectroscopy system for defect studies in wide-bandgap semiconductors. Review of Scientific Instruments, 90(6), Article ID 063903.
Open this publication in new window or tab >>High-temperature deep-level transient spectroscopy system for defect studies in wide-bandgap semiconductors
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2019 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 90, no 6, article id 063903Article in journal (Refereed) Published
Abstract [en]

Full investigation of deep defect states and impurities in wide-bandgap materials by employing commercial transient capacitance spectroscopy is a challenge, demanding very high temperatures. Therefore, a high-temperature deep-level transient spectroscopy (HT-DLTS) system was developed for measurements up to 1100 K. The upper limit of the temperature range allows for the study of deep defects and trap centers in the bandgap, deeper than previously reported by DLTS characterization in any material. Performance of the system was tested by carrying out measurements on the well-known intrinsic defects in n-type 4H-SiC in the temperature range 300-950 K. Experimental observations performed on 4H-SiC Schottky diodes were in good agreement with the literature. However, the DLTS measurements were restricted by the operation and quality of the electrodes.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-255499 (URN)10.1063/1.5097755 (DOI)000474601100062 ()31255019 (PubMedID)2-s2.0-85067838307 (Scopus ID)
Note

QC 20190925

Available from: 2019-09-25 Created: 2019-09-25 Last updated: 2019-09-25Bibliographically approved
Linnarsson, M., Hallén, A. & Vines, L. (2019). Influence of a thin amorthous layer on de-channeling during aluminum implantation at different temperatures into 4H-SiC. Applied Physics A: Materials Science & Processing, 125(12), Article ID 849.
Open this publication in new window or tab >>Influence of a thin amorthous layer on de-channeling during aluminum implantation at different temperatures into 4H-SiC
2019 (English)In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 125, no 12, article id 849Article in journal (Refereed) Published
Abstract [en]

Ion implantation is an important technique in semiconductor processing and has become a key technology for 4H-SiC devices. Today, aluminum (Al) implantations are routinely used for p-type contacts, p(+)-emitters, terminations and many other applications. However, in all crystalline materials, quite a few ions find a path along a crystal channel, so-called channeling, and these ions travel deep into the crystal. This paper reports on the channeling phenomenon during Al implantation into 4H-SiC, and in particular, the influence of a thin native oxide will be discussed in detail. The effects of thermal lattice vibrations for implantations performed at elevated temperatures will also be elucidated. 100 keV Al ions have been implanted along the [000-1] direction employing samples with 4 degrees miscut. Before implantation, the samples have been aligned using the blocking pattern of backscattered protons. Secondary ion mass spectrometry has been used to record the Al depth distribution. To predict implantation profiles and improve understanding of the role of crystal structure, simulations were performed using the Monte-Carlo binary collision approximation code SIIMPL. Our results show that a thin surface layer of native oxide, less than 1 nm, has a decisive role for de-channeling of aligned implantations. Further, as expected, for implantations at elevated temperatures, a larger degree of de-channeling from major axes is present due to increased thermal vibrations and the penetration depth of channeled aluminum ions is reduced. The values for the mean-square atomic displacements at elevated temperatures have been extracted from experimental depth profiles in combination with simulations.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2019
National Category
Physical Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-264238 (URN)10.1007/s00339-019-3144-1 (DOI)000498210100003 ()2-s2.0-85075212151 (Scopus ID)
Funder
Swedish Research Council, E0510501Swedish Research Council, 821-2012-5144Swedish Research Council, 2017-00646-9Swedish Foundation for Strategic Research , RIF14-0053The Research Council of Norway, 251131The Research Council of Norway, 245963
Note

QC 20191216

Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2020-01-02Bibliographically approved
Linnarsson, M., Hallén, A. & Vines, L. (2019). Intentional and unintentional channeling during implantation of 51V ions into 4H-SiC. Semiconductor Science and Technology, 34, 1-10, Article ID 115006.
Open this publication in new window or tab >>Intentional and unintentional channeling during implantation of 51V ions into 4H-SiC
2019 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 34, p. 1-10, article id 115006Article in journal (Refereed) Published
Abstract [en]

Ion implantation is a commonly used process step in 4H-SiC device manufacturing to implement precise concentrations of dopant atoms in selected areas and depths. This paper reports on vanadium (V) implantation into 4H-SiC(0001) and how the crystal lattice, with preferential directions, channels, for the ions, will influence the final dopant distribution. Concentration versus depth profiles of V-ions, intentionally and unintentionally channelled, has been recorded by secondary ion mass spectrometry. Ion implantations have been performed between 50 and 300 keV at various impact angles and fluence at room temperature as well as at elevated temperatures. Before ion implantation, the samples were aligned utilizing the blocking pattern of 100 keV backscattered protons. In addition to the aligned implantations, our standard beam line for ion implantation has been used for implantations in a 'random' direction using the wafer miscut angle of 4 degrees. The electronic stopping has been determined from these 'random' cases and the values have been used in 3D simulations to predict preferential crystallographic directions using SIIMPL, a Monte Carlo simulation code based on the binary collision approximation. The results show that, independent of the used impact angle there is always a probability that the vanadium ions will be steered into the [000-1] and the family of < 11-2-3 > crystal directions and therefore penetrate deep into the sample, resulting in unwanted 'spikes'. If the implantation is performed at elevated temperatures, a larger degree of dechanneling is present due to increased thermal vibrations and the penetration depth of vanadium is slightly reduced.

Keywords
aligned ion implantation; Monte-Carlo simulation; electronic stopping; binar collision approximation; SIMS
National Category
Physical Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-264235 (URN)10.1088/1361-6641/ab4163 (DOI)000507379500006 ()2-s2.0-85076049005 (Scopus ID)
Funder
Swedish Research Council, E0510501Swedish Research Council, 821-2012-5144Swedish Research Council, 2017-00646-9Swedish Foundation for Strategic Research , RIF14-0053The Research Council of Norway, NORFAB 197411/v30
Note

QC 20191204

Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2020-03-09Bibliographically approved
Woerle, J., Prokscha, T., Hallén, A. & Grossner, U. (2019). Interaction of low-energy muons with defect profiles in proton-irradiated Si and 4H-SiC. Physical Review B, 100(11), Article ID 115202.
Open this publication in new window or tab >>Interaction of low-energy muons with defect profiles in proton-irradiated Si and 4H-SiC
2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 100, no 11, article id 115202Article in journal (Refereed) Published
Abstract [en]

Muon spin rotation (mu SR) with low-energy muons is a powerful nuclear method where electrical and magnetic properties of thin films can be investigated in a depth-resolved manner. Here, we present a study on proton-irradiated Si and 4H-SiC where the formation of the hydrogen-like muonium (Mu) is analyzed as a function of the proton dose. While the Mu formation is strongly suppressed in the highly defective region of the shallow proton stopping profile, the Mu signal quickly recovers for higher muon energies where the muons reach the untreated semiconductor bulk. A lower sensitivity limit of low-energy mu SR to crystal defects of around 10(17) to 10(18) cm(-3) is estimated. Our results demonstrate the high potential of this technique to nondestructively probe near-surface regions without the need for electronic device fabrication and to provide valuable complementary information when investigating defects in semiconductors.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-261305 (URN)10.1103/PhysRevB.100.115202 (DOI)000486636700004 ()2-s2.0-85072805848 (Scopus ID)
Note

QC 20191008

Available from: 2019-10-08 Created: 2019-10-08 Last updated: 2019-10-08Bibliographically approved
Hallén, A., Linnarsson, M. & Vines, L. (2019). Recent advances in the doping of 4H-SiC by channeling ion implantation. In: Silicon Carbide and Related Materials 2018: . Paper presented at 12th European Conference on Silicon Carbide and Related Materials, ECSCRM 2018; Birmingham; United Kingdom; 2 September 2018 through 6 September 2018 (pp. 375-381). Trans Tech Publications Inc., 963
Open this publication in new window or tab >>Recent advances in the doping of 4H-SiC by channeling ion implantation
2019 (English)In: Silicon Carbide and Related Materials 2018, Trans Tech Publications Inc., 2019, Vol. 963, p. 375-381Conference paper, Published paper (Refereed)
Abstract [en]

The effect of lattice thermal vibrations on the channeling of 100 keV Al ions in 4H-SiC is investigated. By implanting at room temperature in the direction, the depth distribution of the incident ions is shown to be about 7 times deeper than for random implantations. At higher implantation temperatures, the channeling is reduced by the lattice vibrations and, for instance, at 600 °C implantation the distribution is about 3-4 times deeper than for a RT random implantation. The results are of technological interest for further development of implantation technology for 4H-SiC device manufacturing.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2019
Series
Materials Science Forum, ISSN 0255-5476 ; 963
National Category
Physical Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-264360 (URN)10.4028/www.scientific.net/MSF.963.375 (DOI)2-s2.0-85071888219 (Scopus ID)9783035713329 (ISBN)
Conference
12th European Conference on Silicon Carbide and Related Materials, ECSCRM 2018; Birmingham; United Kingdom; 2 September 2018 through 6 September 2018
Note

QC 20191205

Available from: 2019-11-26 Created: 2019-11-26 Last updated: 2019-12-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8760-1137

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