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Moskalenko, Evgenii
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Publications (10 of 55) Show all publications
Hsu, C.-W., Moskalenko, E., Eriksson, M., Lundskog, A., Karlsson, F. K., Forsberg, U., . . . Holtz, P.-O. (2013). The charged exciton in an InGaN quantum dot on a GaN pyramid. Applied Physics Letters, 103(1)
Open this publication in new window or tab >>The charged exciton in an InGaN quantum dot on a GaN pyramid
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2013 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 1Article in journal (Refereed) Published
Abstract [en]

The emission of a charged exciton in an InGaN quantum dot (QD) on top of a GaN pyramid is identified experimentally. The intensity of the charged exciton exhibits the expected competition with that of the single exciton, as observed in temperature-dependent micro-photoluminescence measurements, performed with different excitation energies. The non-zero charge state of this complex is further supported by time resolved micro-photoluminescence measurements, which excludes neutral alternatives of biexciton. The potential fluctuations in the vicinity of the QD that localizes the charge carriers are proposed to be responsible for the unequal supply of electrons and holes into the QD.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-95961 (URN)10.1063/1.4812984 (DOI)000321497200036 ()
Note

Funding Agencies|NANO-N consortium||Swedish Foundation for Strategic Research (SSF)||

Available from: 2013-08-19 Created: 2013-08-12 Last updated: 2017-12-06
Amloy, S., Moskalenko, E., Eriksson, M., Karlsson, K. F., Chen, Y. T., Chen, K. H., . . . Holtz, P.-O. (2012). Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot. Applied Physics Letters, 101(6)
Open this publication in new window or tab >>Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot
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2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 6Article in journal (Refereed) Published
Abstract [en]

The dynamics of the exciton and the biexciton related emission from a single InGaN quantum dot (QD) have been measured by time-resolved microphotoluminescence spectroscopy. An exciton-biexciton pair of the same QD was identified by the combination of power dependence and polarization-resolved spectroscopy. Moreover, the spectral temperature evolution was utilized in order to distinguish the biexciton from a trion. Both the exciton and the biexciton related emission reveal mono-exponential decays corresponding to time constants of similar to 900 and similar to 500 ps, respectively. The obtained lifetime ratio of similar to 1.8 indicates that the QD is small, with a size comparable to the exciton Bohr radius.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-84908 (URN)10.1063/1.4742343 (DOI)000307862400022 ()
Note

Funding Agencies|Thaksin University in Thailand||Swedish Research Council (VR)||Swedish Foundation for Strategic Research (SSF)||Knut and Alice Wallenberg Foundation||

Available from: 2012-10-26 Created: 2012-10-26 Last updated: 2017-12-07
Holtz, P.-O., Hsu, C.-W., Larsson, L. A., Karlsson, K. F., Dufåker, D., Lundskog, A., . . . Pelucchi, E. (2012). Optical characterization of individual quantum dots. Physica. B, Condensed matter, 407(10), 1472-1475
Open this publication in new window or tab >>Optical characterization of individual quantum dots
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2012 (English)In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 407, no 10, p. 1472-1475Article in journal (Refereed) Published
Abstract [en]

Optical characterization of single quantum dots (QDs) by means of micro-photoluminescence (mu PL) will be reviewed. Both QDs formed in the Stranski-Krastanov mode as well as dots in the apex of pyramidal structures will be presented. For InGaAs/GaAs dots, several excitonic features with different charge states will be demonstrated. By varying the magnitude of an external electric or magnetic field and/or the temperature, it has been demonstrated that the transportation of carriers is affected and accordingly the charge state of a single QD can be tuned. In addition, we have shown that the charge state of the QD can be controlled also by pure optical means, i.e. by altering the photo excitation conditions. Based on the experience of the developed InAs/GaAs QD system, similar methods have been applied on the InGaN/GaN QD system. less thanbrgreater than less thanbrgreater thanThe coupling of LO phonons to the QD emission is experimentally examined for both charged and neutral excitons in single InGaAs/GaAs QDs in the apex of pyramidal structures. It is shown that the positively charged exciton exhibits a significantly weaker LO phonon coupling in the mu PL spectra than the neutral and negatively charged species, a fact, which is in consistency with model simulations performed.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
Quantum dots, Pyramid, Exciton, Photoluminescence
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-77523 (URN)10.1016/j.physb.2011.09.064 (DOI)000303149600005 ()
Note

Funding Agencies|Swedish Research Council (VR)||Swedish Foundation for Strategic Research (SSF)||Nano-N consortium||Science Foundation Ireland|05/IN.1/I25|Knut and Alice Wallenberg Foundation||INSPIRE||

Available from: 2012-05-28 Created: 2012-05-22 Last updated: 2017-12-07
Moskalenko, E., Larsson, L. & Holtz, P.-O. (2011). Circularly polarized emission from ensembles of InAs/GaAs quantum dots. Journal of Applied Physics, 110(1), 013510
Open this publication in new window or tab >>Circularly polarized emission from ensembles of InAs/GaAs quantum dots
2011 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 1, p. 013510-Article in journal (Refereed) Published
Abstract [en]

We present a low-temperature micro-photoluminescence (mu-PL) study of ensembles of InAs/GaAs quantum dots (QDs) with respect to its circular polarization (rho(c)) for a manifold of experimental conditions such as single or dual laser excitation, different excitation energies (h upsilon(ex)), varying excitation powers (P(ex)) of both lasers, and with or without an external magnetic field (B(ext)). It is demonstrated that an essential rho(c) (less than= 40%) could be recorded depending on P(ex), even at B(ext) = 0 for h upsilon(ex) exceeding the PL energy of the wetting layer (E(WL)), while rho(c) remains negligible for h upsilon(ex) less than E(WL). To explain the data obtained, a model is developed according to which a nuclear magnetic field (B(N)) is created in the QDs by spin-polarized electrons. The B(N) plays a crucial role in the preservation of the electron spin, which otherwise effectively relaxes due to the presence of the anisotropic electron-hole exchange interaction (omega(ex)). The application of an additional infra-red laser gives rise to a population of excess holes in the QDs, thus producing positively charged excitons. In this case, omega(ex) = 0 and accordingly, rho(c) approximate to 40% at B(ext) = 0 is recorded, even for excitation with h upsilon(ex) less than E(WL).

Place, publisher, year, edition, pages
American Institute of Physics, 2011
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-69808 (URN)10.1063/1.3599853 (DOI)000292776500027 ()
Note

Original Publication: Evgenii Moskalenko, L.A. Larsson and Per-Olof Holtz, Circularly polarized emission from ensembles of InAs/GaAs quantum dots, 2011, Journal of Applied Physics, (110), 1, 013510. http://dx.doi.org/10.1063/1.3599853 Copyright: American Institute of Physics http://www.aip.org/

Available from: 2011-08-10 Created: 2011-08-08 Last updated: 2017-12-08
Larsson, A., Moskalenko, E. & Holtz, P.-O. (2011). Manipulating the Spin Polarization of Excitons in a Single Quantum Dot by Optical Means. Applied Physics Letters, 98(7), 071906
Open this publication in new window or tab >>Manipulating the Spin Polarization of Excitons in a Single Quantum Dot by Optical Means
2011 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 7, p. 071906-Article in journal (Refereed) Published
Abstract [en]

Circular polarization studies of photoluminescence from the neutral (X0) and the positively charged (X+) exciton are reported for individual InAs/GaAs quantum dots (QDs). High polarization degrees, 60 % for X0 and 73 % for X+, were recorded without any external magnetic field applied. These studies show that that the QD polarization and population dynamics are controllable either by varying the photo-excitation intensity, or by using a second IR laser excitation.

Place, publisher, year, edition, pages
American Institute of Physics, 2011
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-64725 (URN)10.1063/1.3554422 (DOI)000287507200017 ()
Note
Original Publication: Arvid Larsson, Evgenii Moskalenko and Per-Olof Holtz, Manipulating the Spin Polarization of Excitons in a Single Quantum Dot by Optical Means, 2011, Applied Physics Letters, (98), 7, 071906. http://dx.doi.org/10.1063/1.3554422 Copyright: American Institute of Physics http://www.aip.org/ Available from: 2011-02-03 Created: 2011-02-03 Last updated: 2017-12-11Bibliographically approved
Larsson, L. A., Moskalenko, E. S. & Holtz, P.-O. (2011). Quantum Dot Charging By Means Of Temperature And Magnetic Field. In: : . Paper presented at 30th International Conference on The Physics of Semiconductors (ICPS) (pp. 433-434). , 1399(1)
Open this publication in new window or tab >>Quantum Dot Charging By Means Of Temperature And Magnetic Field
2011 (English)Conference paper, Published paper (Other academic)
Abstract [en]

A micro‐photoluminescence study of individual InAs/GaAs quantum dots is presented. It is demonstrated that by varying the strength of an applied magnetic field and/or the temperature, the charge state of a quantum dot can be tuned. The charge tuning mechanism is shown to be due to the modification of the electron and hole transport in the wetting layer plane prior to their capture into the quantum dot.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-118732 (URN)10.1063/1.3666439 (DOI)978-0-7354-1002-2 (ISBN)
Conference
30th International Conference on The Physics of Semiconductors (ICPS)
Available from: 2015-06-03 Created: 2015-06-03 Last updated: 2015-06-18
Moskalenko, E., Larsson, L. A. & Holtz, P.-O. (2011). Spin polarization of the neutral exciton in a single quantum dot. SUPERLATTICES AND MICROSTRUCTURES, 49(3), 294-299
Open this publication in new window or tab >>Spin polarization of the neutral exciton in a single quantum dot
2011 (English)In: SUPERLATTICES AND MICROSTRUCTURES, ISSN 0749-6036, Vol. 49, no 3, p. 294-299Article in journal (Refereed) Published
Abstract [en]

While efficient nuclear polarization has earlier been reported for the charged exciton in InAs/GaAs quantum dots at zero external magnetic field, we report here on a surprisingly high degree of circular polarization, up to approximate to 60%, for the neutral exciton emission in individual InAs/GaAs dots. This high degree of polarization is explained in terms of the appearance of an effective nuclear magnetic field which stabilizes the electron spin. The nuclear polarization is manifested in experiments as a detectable Overhauser shift. In turn, the nuclei located inside the dot are exposed to an effective electron magnetic field, the Knight field. This nuclear polarization is understood as being due to the dynamical nuclear polarization by an electron localized in the QD. The high degree of polarization for the neutral exciton is also suggested to be due to separate in-time capture of electrons and holes into the QD.

Place, publisher, year, edition, pages
Elsevier Science B.V., Amsterdam, 2011
Keywords
Quantum dot, Exciton, Polarization, Photoluminescence, Spin
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-67540 (URN)10.1016/j.spmi.2010.06.012 (DOI)000288929500020 ()
Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2013-05-07
Larsson, L. A., Moskalenko, E. S. & Holtz, P.-O. (2011). Spin Polarizing Neutral Excitons In Quantum Dots. In: : . Paper presented at 30TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS (pp. 435-436). , 1399(1)
Open this publication in new window or tab >>Spin Polarizing Neutral Excitons In Quantum Dots
2011 (English)Conference paper, Published paper (Other academic)
Abstract [en]

A high degree of spin polarization for the neutral exciton in individual InAs quantum dots, without any external magnetic field applied, is demonstrated. The polarization mechanism is shown to be due to the difference in capture time into the QD for the electrons and holes after photo excitation in the wetting layer. This leads to optical pumping of the QD nuclei by spin polarized electrons and hence suppression of the anisotropic electron—hole exchange interaction.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-118731 (URN)10.1063/1.3666440 (DOI)978-0-7354-1002-2 (ISBN)
Conference
30TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS
Available from: 2015-06-03 Created: 2015-06-03 Last updated: 2015-06-18
Moskalenko, E., Larsson, A. & Holtz, P.-O. (2010). Spin polarization of neutral excitons in quantum dots: the role of the carrier collection area. Nanotechnology, 21(34)
Open this publication in new window or tab >>Spin polarization of neutral excitons in quantum dots: the role of the carrier collection area
2010 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, NANOTECHNOLOGY, Vol. 21, no 34Article in journal (Refereed) Published
Abstract [en]

A high degree (approximate to 55%) of circular polarization has been observed for the neutral exciton in InAs/GaAs quantum dots (QDs). The possibility to record non- zero polarization of the neutral exciton is explained in terms of different capture times of the light electron compared with the heavier holes into the QDs from the wetting layer. This interpretation is supported by the progressive reduction of the polarization degree with increasing QD density, and also with increasing temperature.

Place, publisher, year, edition, pages
Institute of Physics, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-58644 (URN)10.1088/0957-4484/21/34/345401 (DOI)000280632500009 ()
Note
Original Publication: Evgenii Moskalenko, Arvid Larsson and Per-Olof Holtz, Spin polarization of neutral excitons in quantum dots: the role of the carrier collection area, 2010, NANOTECHNOLOGY, (21), 34, 345501. http://dx.doi.org/10.1088/0957-4484/21/34/345401 Copyright: Institute of Physics; 1999 http://www.iop.org/ Available from: 2010-08-22 Created: 2010-08-20 Last updated: 2017-12-12Bibliographically approved
Moskalenko, E., Larsson, A., Larsson, M., Holtz, P.-O., Schoenfeld, W. V. & Petroff, P. M. (2009). Comparative Magneto-Photoluminescence Study of Ensembles and of Individual InAs Quantum Dots. Nano letters (Print), 9(1), 353-359
Open this publication in new window or tab >>Comparative Magneto-Photoluminescence Study of Ensembles and of Individual InAs Quantum Dots
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2009 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 9, no 1, p. 353-359Article in journal (Refereed) Published
Abstract [en]

We report on magneto-photoluminescence studies of InAs/GaAs quantum dots (QDs) of considerably different densities, from dense ensembles down to individual dots. It is found that a magnetic field applied in Faraday geometry decreases the photoluminescence (PL) intensity of OD ensembles, which is not accompanied by the corresponding increase of PL signal of the wetting layer on which ON are grown. The model suggested to explain these data assumes considerably different strengths of suppression of electron and hole fluxes by a magnetic field. This idea has been successfully checked in experiments on individual ON, where the PL spectra allow to directly monitor the charge state of a OD and, hence, to conclude about relative magnitudes of electron and hole fluxes toward the QD. Comparative studies of different individual QDs have revealed that the internal electric field in the sample (which was altered in the experiments in a controllable way) together with an external magnetic field will determine the charge state and emission intensity of the QDs.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-16615 (URN)10.1021/nl803148q (DOI)
Available from: 2009-02-07 Created: 2009-02-06 Last updated: 2017-12-14Bibliographically approved
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