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

Direct link
BETA
Son, Tien Nguyen
Alternative names
Publications (10 of 163) Show all publications
Nagy, R., Widmann, M., Niethammer, M., Dasari, D. B. .., Gerhardt, I., Soykal, O. O., . . . Wrachtrup, J. (2018). Quantum Properties of Dichroic Silicon Vacancies in Silicon Carbide. Physical Review Applied, 9(3), Article ID 034022.
Open this publication in new window or tab >>Quantum Properties of Dichroic Silicon Vacancies in Silicon Carbide
Show others...
2018 (English)In: Physical Review Applied, E-ISSN 2331-7019, Vol. 9, no 3, article id 034022Article in journal (Refereed) Published
Abstract [en]

Although various defect centers have displayed promise as either quantum sensors, single photon emitters, or light-matter interfaces, the search for an ideal defect with multifunctional ability remains open. In this spirit, we study the dichroic silicon vacancies in silicon carbide that feature two well-distinguishable zero-phonon lines and analyze the quantum properties in their optical emission and spin control. We demonstrate that this center combines 40% optical emission into the zero-phonon lines showing the contrasting difference in optical properties with varying temperature and polarization, and a 100% increase in the fluorescence intensity upon the spin resonance, and long spin coherence time of their spin-3/2 ground states up to 0.6 ms. These results single out this defect center as a promising system for spin-based quantum technologies.

National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-147280 (URN)10.1103/PhysRevApplied.9.034022 (DOI)000428168800003 ()
Available from: 2018-04-12 Created: 2018-04-12 Last updated: 2018-04-24
Ivády, V., Davidsson, J., Nguyen, T. S., Ohshima, T., Abrikosov, I. & Gali, A. (2017). Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide. Physical Review B, 96(16), Article ID 161114.
Open this publication in new window or tab >>Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide
Show others...
2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, no 16, article id 161114Article in journal (Refereed) Published
Abstract [en]

The identification of a microscopic configuration of point defects acting as quantum bits is a key step in the advance of quantum information processing and sensing. Among the numerous candidates, silicon-vacancy related centers in silicon carbide (SiC) have shown remarkable properties owing to their particular spin-3/2 ground and excited states. Although, these centers were observed decades ago, two competing models, the isolated negatively charged silicon vacancy and the complex of negatively charged silicon vacancy and neutral carbon vacancy [Phys. Rev. Lett. 115, 247602 (2015)], are still argued as an origin. By means of high-precision first-principles calculations and high-resolution electron spin resonance measurements, we here unambiguously identify the Si-vacancy related qubits in hexagonal SiC as isolated negatively charged silicon vacancies. Moreover, we identify the Si-vacancy qubit configurations that provide room-temperature optical readout.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2017
National Category
Other Physics Topics
Identifiers
urn:nbn:se:liu:diva-142978 (URN)10.1103/PhysRevB.96.161114 (DOI)000413848300001 ()
Note

Funding Agencies|Knut & Alice Wallenberg Foundation project Strong Field Physics and New States of Matter; Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Swedish Research Council [VR 2016-04068]; Carl-Trygger Stiftelse for Vetenskaplig Forskning [CTS 15:339]; JSPS KAKENHI [A 17H01056]; Hungarian NKFIH Grant [NVKP_16-1-2016-0152958]

Available from: 2017-11-13 Created: 2017-11-13 Last updated: 2018-01-25Bibliographically approved
Duc Tran, T., Pozina, G., Nguyen, T. S., Kordina, O., Janzén, E., Ohshima, T. & Hemmingsson, C. (2016). Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy. Journal of Applied Physics, 119(9)
Open this publication in new window or tab >>Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy
Show others...
2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 9Article in journal (Refereed) Published
Abstract [en]

By minority carrier transient spectroscopy on as-grown n-type bulk GaN produced by halide vapor phase epitaxy (HVPE) one hole trap labelled H1 (EV + 0.34 eV) has been detected. After 2 MeV-energy electron irradiation, the concentration of H1 increases and at fluences higher than 5×1014 cm-2, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (EC - 0.12 eV) and T2 (EC - 0.23 eV) increases. By studying the increase of the concentration versus electron irradiation fluences, the introduction rate of T1 and T2 using 2 MeV-energy electrons was determined to 7X10-3 cm-1 and 0.9 cm-1, respectively. Due to the low introduction rate of T1 and the low threading dislocation density in the HVPE bulk GaN material, it is suggested that the defect is associated with a primary defect decorating extended structural defects. The high introduction rate of the trap H1 suggests that the H1 defect is associated with a primary intrinsic defect or a complex.

Keyword
Deep level, GaN, DLTS, irradiation
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-121709 (URN)10.1063/1.4943029 (DOI)000372351900075 ()
Note

Funding agencies:  Swedish Research Council (VR); Swedish Energy Agency

Vid tiden för disputation förelåg publikationen som manuskript

Available from: 2015-10-02 Created: 2015-10-02 Last updated: 2017-12-01Bibliographically approved
Booker, I. D., Janzén, E., Son, N. T., Hassan, J., Stenberg, P. & Sveinbjörnsson, E. (2016). Donor and double donor transitions of the carbon vacancy related EH6/7 deep level in 4H-SiC. Journal of Applied Physics, 119(23), Article ID 235703.
Open this publication in new window or tab >>Donor and double donor transitions of the carbon vacancy related EH6/7 deep level in 4H-SiC
Show others...
2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 23, article id 235703Article in journal (Refereed) Published
Abstract [en]

Using medium- and high-resolution multi-spectra fitting of deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS), optical O-DLTS and optical-electrical (OE)-MCTS measurements, we show that the EH6∕7 deep level in 4H-SiC is composed of two strongly overlapping, two electron emission processes with thermal activation energies of 1.49 eV and 1.58 eV for EH6 and 1.48 eV and 1.66 eV for EH7. The electron emission peaks of EH7 completely overlap while the emission peaks of EH6 occur offset at slightly different temperatures in the spectra. OE-MCTS measurements of the hole capture cross section σp 0(T) in p-type samples reveal a trap-Auger process, whereby hole capture into the defect occupied by two electrons leads to a recombination event and the ejection of the second electron into the conduction band. Values of the hole and electron capture cross sections σn(T) and σp(T) differ strongly due to the donor like nature of the deep levels and while all σn(T) have a negative temperature dependence, the σp(T) appear to be temperature independent. Average values at the DLTS measurement temperature (∼600 K) are σn 2+(T) ≈ 1 × 10−14 cm2, σn +(T) ≈ 1 × 10−14 cm2, and σp 0(T) ≈ 9 × 10−18 cm2 for EH6 and σn 2+(T) ≈ 2 × 10−14 cm2, σn +(T) ≈ 2 × 10−14 cm2, σp 0(T) ≈ 1 × 10−20 cm2 for EH7. Since EH7 has already been identified as a donor transition of the carbon vacancy, we propose that the EH6∕7 center in total represents the overlapping first and second donor transitions of the carbon vacancy defects on both inequivalent lattice sites.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
Keyword
4H-SiC, DLTS, MCTS, Carbon vacancy, EH6/7; Z1/2, UT-1, Negative-U, Trap Auger, Deep level
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-121544 (URN)10.1063/1.4954006 (DOI)000379038800035 ()
Funder
Swedish Foundation for Strategic Research Swedish Research Council
Note

At the time for thesis presentation publication was in status: Manuscript

Funding agencies: Swedish Foundation for Strategic Research (SSF); Swedish Research Council (VR)

Available from: 2015-09-24 Created: 2015-09-24 Last updated: 2017-12-01Bibliographically approved
Duc Tran, T., Pozina, G., Nguyen, T. S., Ohshima, T., Janzén, E. & Hemmingsson, C. (2016). Electronic properties of defects in high-fluence electron irradiated bulk GaN. Physica status solidi. B, Basic research, 253(3), 521-526
Open this publication in new window or tab >>Electronic properties of defects in high-fluence electron irradiated bulk GaN
Show others...
2016 (English)In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 253, no 3, p. 521-526Article in journal (Refereed) Published
Abstract [en]

Using deep level transient spectroscopy, deep levels and capture cross sections of defects introduced by high-fluence electron irradiation of thick halide vapour phase epitaxy grown GaN has been studied. After irradiation with 2 MeV electrons to a high-fluence of 5×1016 cm-2, four deep trap levels, labelled T1 (EC – 0.13 eV), T2 (EC – 0.18 eV), T3 (EC – 0.26 eV) T4 and a broad band of peaks consisting of at least two levels could be observed. These defects, except T1 and T3, were annealed out after annealing at 650 K for 2 hours. The capture cross section is found to be temperature independent for T2 and T3, while T1 shows an decresing capture cross section with increasing temperature, suggesting that electron capturing to this deep level is governed by a cascade capturing process.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keyword
Deep level, GaN, DLTS, irradiation
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-121707 (URN)10.1002/pssb.201552521 (DOI)000371634800018 ()
Note

Funding agencies: Swedish Research Council (VR); Swedish Energy Agency

Available from: 2015-10-02 Created: 2015-10-02 Last updated: 2017-12-01Bibliographically approved
Widmann, M., Lee, S.-Y., Rendler, T., Tien Son, N., Fedder, H., Paik, S., . . . Wrachtrup, J. (2015). Coherent control of single spins in silicon carbide at room temperature. Nature Materials, 14(2), 164-168
Open this publication in new window or tab >>Coherent control of single spins in silicon carbide at room temperature
Show others...
2015 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 14, no 2, p. 164-168Article in journal (Refereed) Published
Abstract [en]

Spins in solids are cornerstone elements of quantum spintronics(1). Leading contenders such as defects in diamond(2-5) or individual phosphorus dopants in silicon(6) have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems(5):it has a large bandgap with deep defects(7-9) and benefits from mature fabrication techniques(10-12). Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology.

Place, publisher, year, edition, pages
Nature Publishing Group, 2015
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-114990 (URN)10.1038/NMAT4145 (DOI)000348600200012 ()25437256 (PubMedID)
Note

Funding Agencies|EU via SQUTEC; EU via SIQS; EU via QINVC; DARPA via QuASAR; Max Planck Society; DFG via SPP [1601]; DFG via Forschergruppe [FOR1493]; Lendulet programme of the Hungarian Academy of Sciences; Hungarian OTKA grant [K101819, K106114]; Knut and Alice Wallenberg Foundation; Linkoping Linnaeus Initiative for Novel Functionalized Materials; Ministry of Education, Science, Sports and Culture in Japan [26286047]; NKBRP (973 Program) [2014CB848700]; NSFC [11121403]

Available from: 2015-03-11 Created: 2015-03-06 Last updated: 2017-12-04
Zeglio, E., Vagin, M., Musumeci, C., Ajjan, F., Gabrielsson, R., Trinh, X. t., . . . Inganäs, O. (2015). Conjugated Polyelectrolyte Blends for Electrochromic and Electrochemical Transistor Devices. Chemistry of Materials, 27(18), 6385-6393
Open this publication in new window or tab >>Conjugated Polyelectrolyte Blends for Electrochromic and Electrochemical Transistor Devices
Show others...
2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 18, p. 6385-6393Article in journal (Refereed) Published
Abstract [en]

Two self-doped conjugated polyelectrolytes, having semiconducting and metallic behaviors, respectively, have been blended from aqueous solutions in order to produce materials with enhanced optical and electrical properties. The intimate blend of two anionic conjugated polyelectrolytes combine the electrical and optical properties of these, and can be tuned by blend stoichiometry. In situ conductance measurements have been done during doping of the blends, while UV vis and EPR spectroelectrochemistry allowed the study of the nature of the involved redox species. We have constructed an accumulation/depletion mode organic electrochemical transistor whose characteristics can be tuned by balancing the stoichiometry of the active material.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2015
National Category
Materials Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-122212 (URN)10.1021/acs.chemmater.5b02501 (DOI)000361935000028 ()
Note

Funding Agencies|Marie Curie network "Renaissance"; Knut and Alice Wallenberg foundation through Wallenberg Scholar grant; Swedish Research Council [VR-2014-3079, D0556101]; Carl Trygger Foundation [CTS 12:206]

Available from: 2015-10-26 Created: 2015-10-23 Last updated: 2017-12-01
Trinh, X. T., Ivády, V., Kawahara, K., Suda, J., Kimoto, T., Gali, Á., . . . Son, N. T. (2015). Electron paramagnetic resonance studies of carbon interstitial related defects in 4H-SiC.
Open this publication in new window or tab >>Electron paramagnetic resonance studies of carbon interstitial related defects in 4H-SiC
Show others...
2015 (English)Manuscript (preprint) (Other academic)
Abstract [en]

In n-type 4H-SiC grown by chemical vapor deposition and irradiated by low-energy (250 keV) electrons, an electron paramagnetic resonance center, labeled EI8a, was observed at room temperature. A short anneal at temperatures in the range of 300-500 °C in darkness changes EI8a to a new center, labeled EI8b, which can be converted back by illumination at room temperature. We show that EI8a and EI8b are the two different configurations of the same defect, labeled EI8, with C1h symmetry and an electron spin S=1/2. The EI8 center is stable up to ~650 °C and annealed out at ~800 °C. Based on the observed hyperfine structures due to the hyperfine interaction between the electron spin and the nuclear spins of four 29Si atoms and three 13C atoms, the EI8 center is suggested to be related to a carbon interstitial cluster.

National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-117880 (URN)
Available from: 2015-05-12 Created: 2015-05-12 Last updated: 2015-05-12Bibliographically approved
Feneberg, M., Nguyen, S. T. & Kakanakova-Gueorguie, A. (2015). Exciton luminescence in AIN triggered by hydrogen and thermal annealing. Applied Physics Letters, 106(24), 242101
Open this publication in new window or tab >>Exciton luminescence in AIN triggered by hydrogen and thermal annealing
2015 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 24, p. 242101-Article in journal (Refereed) Published
Abstract [en]

Exciton recombination bands in homoepitaxial AIN layers are strongly dependent on the presence of hydrogen. By thermal treatment under hydrogen-free and hydrogen-rich ambient, respectively, several sharp bound exciton lines are modulated in intensity reversibly. In contrast, the exciton bound at the neutral donor silicon remains unaffected. The mechanism causing these effects is most probably hydrogen in-and out-diffusion into the AIN sample. The main factor determining hydrogenation of AIN layers is found to be molecular H-2 in contrast to NH3. We find hints that carbon incorporation into AIN may be closely related with that of hydrogen. Besides photoluminescence spectra of exciton bands, our model is supported by theoretical reports and comparison to the case of hydrogen in GaN.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2015
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-120167 (URN)10.1063/1.4922723 (DOI)000356618700019 ()
Note

Funding Agencies|Swedish Research Council (VR); Swedish Governmental Agency for Innovation Systems (VINNOVA); Linkoping Linnaeus Initiative for Novel Functional Materials (LiLi-NFM, VR)

Available from: 2015-07-13 Created: 2015-07-13 Last updated: 2017-12-04
Christle, D. J., Falk, A. L., Andrich, P., Klimov, P. V., ul-Hassan, J., Tien Son, N., . . . Awschalom, D. D. (2015). Isolated electron spins in silicon carbide with millisecond coherence times. Nature Materials, 14(2), 160-163
Open this publication in new window or tab >>Isolated electron spins in silicon carbide with millisecond coherence times
Show others...
2015 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 14, no 2, p. 160-163Article in journal (Refereed) Published
Abstract [en]

The elimination of defects from SiC has facilitated its move to the forefront of the optoelectronics and power-electronics industries(1). Nonetheless, because certain SiC defects have electronic states with sharp optical and spin transitions, they are increasingly recognized as a platform for quantum information and nanoscale sensing(2-16). Here, we show that individual electron spins in high-purity monocrystalline 4H-SiC can be isolated and coherently controlled. Bound to neutral divacancy defects(2,3), these states exhibit exceptionally long ensemble Hahn-echo spin coherence times, exceeding 1 ms. Coherent control of single spins in a material amenable to advanced growth and microfabrication techniques is an exciting route towards wafer-scale quantum technologies.

Place, publisher, year, edition, pages
Nature Publishing Group, 2015
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-114989 (URN)10.1038/NMAT4144 (DOI)000348600200011 ()25437259 (PubMedID)
Note

Funding Agencies|NSF; Center for Nanoscale Materials [CNM 39211]; Knut and Alice Wallenberg Foundation; Linkoping Linnaeus Initiative for Novel Functionalized Materials; Swedish Government Strategic Research Area Grant in Materials Science (Advanced Functional Materials); Ministry of Education, Science, Sports and Culture of Japan [26286047]; AFOSR MURI

Available from: 2015-03-11 Created: 2015-03-06 Last updated: 2017-12-04
Organisations

Search in DiVA

Show all publications