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Wyszukujesz frazę "Pakula, J." wg kryterium: Autor


Wyświetlanie 1-10 z 10
Tytuł:
Time Evolution of the Microluminescence Energy οf GaN/AlGaN Quantum Dots
Autorzy:
Surowiecka, K.
Wysmołek, A.
Stępniewski, R.
Bożek, R.
Pakuła, K.
Baranowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1791354.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.67.Hc
Opis:
Time evolution of the microphotoluminescence from low-density GaN/$Al_{x}Ga_{1-x}N$ quantum dots grown by metal organic chemical vapor deposition using in situ etching of AlGaN is presented. The observed effect is related to the energy changes that begin immediately after sample illumination with the exciting laser light and saturate after some time. Typically, the luminescence energy decreases and the change is exponential with characteristic times in a range between several dozen and several hundred seconds. However, sometimes we observed the energy increase with characteristic times in a range between several and a few hundred seconds. The obtained results are discussed in terms of the metastable change of the electric field, induced by spontaneous polarization present in GaN/AlGaN structure (in the growth direction), and strain- or defect-induced changes of the electric field in the vicinity of the dot.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 933-935
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Single GaN/AlGaN Quantum Dot Spectroscopy
Autorzy:
Surowiecka, K.
Wysmołek, A.
Stępniewski, R.
Bożek, R.
Pakuła, K.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/2047382.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.67.Hc
Opis:
Microphotoluminescence of low-density GaN/Al$\text{}_{x}$Ga$\text{}_{1-x}$N quantum dots grown by metal-organic vapor phase epitaxy using in situ etching of AlGaN is presented. The detailed analysis of the emission from these structures enables the observation of pairs of lines separated by the energy up to 3 meV. They behave in a different way under different excitation power that suggests that this doublet structure can be associated with the exciton and trion (or biexciton recombination). It is observed that for different quantum dots the energy of the charged exciton complex emission could be higher or lower than the neutral exciton one. It is discussed in terms of a competition between attractive e-h and repulsive e-e (h-h) Coulomb interaction that occurs because of the existence of the built-in electric field that separates electrons and holes in the dot.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 233-236
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temporal Evolution of Multi-Carrier Complexes in Single GaN/AlGaN Quantum Dots
Autorzy:
Surowiecka, K.
Wysmołek, A.
Stępniewski, R.
Bożek, R.
Pakuła, K.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/2044542.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.67.Hc
Opis:
Microphotoluminescence of low-density GaN/Al$\text{}_{x}$Ga$\text{}_{1-x}$N quantum dots grown by metal-organic vapor phase epitaxy using in situ etching of AlGaN is presented. The narrow lines in the microphotoluminescence spectra due to the single quantum dots are observed. Both energy and intensity of these lines show temporal fluctuations. Statistical analysis based on the correlation matrix allowed us to identify objects, which are affected by photo-induced electric field fluctuations. Relations between emission lines participating in the spectrum are discussed.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 879-884
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-Electron Transition in Homoepitaxial GaN Layers
Autorzy:
Fiorek, A.
Baranowski, J. M.
Wysmołek, A.
Pakuła, K.
Wojdak, M.
Grzegory, I.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/1968067.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Fd
78.55.Cr
Opis:
It is shown that the luminescence mapping is a powerful method to help identify optical transitions. Two-electron transition was identified in the homoepitaxial GaN layer by this technique. It was found that the donor and acceptor bound exciton emissions are spatially displaced and show intensity maxima at different places of the epitaxial layer. It was also found that the 3.45 eV line, suspected as "two-electron transition", follows exactly the donor bound exciton spatial distribution. Donor bound exciton recombines leaving the neutral donor in the excited 2s state. Thus, 1s-2s excitation being equal to 22 meV corresponds to 29 meV hydrogenic donor binding energy. This is the first identification of the two-electron transition in GaN.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 742-744
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth of GaN Metalorganic Chemical Vapour Deposition Layers on GaN Single Crystals
Autorzy:
Pakula, K.
Baranowski, J. M.
Stępniewski, R.
Wysmołek, A.
Grzegory, I.
Jun, J.
Porowski, S.
Sawicki, M.
Starowieyski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1933937.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Fd
78.55.Cr
Opis:
The homoepitaxial growth of GaN layers has been achieved for the first time. Bulk GaN single crystals which have been used as a substrate have been grown from diluted solution of atomic nitrogen in the liquid gallium at 1600°C and at nitrogen pressure of about 15-20 kbar. It is shown that a terrace growth of GaN epitaxial layer has been realized. The high quality of the GaN film has been confirmed by luminescence measurements. The analysis of donor-acceptor and exciton luminescence is presented.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 861-864
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatially Resolved Micro-Luminescence from GaN/AlGaN Quantum Dots
Autorzy:
Chwalisz, B.
Wysmołek, A.
Bożek, R.
Stępniewski, R.
Pakuła, K.
Kossacki, P.
Golnik, A.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/2038084.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.66.Fd
78.67.Hc
75.75.+a
68.65.Hb
Opis:
We report on the optical experiments performed on low density GaN/AlGaN quantum dots grown on sapphire substrate using SiN during the growth process. The existence of quantum dots in the investigated structures was confirmed by atomic force microscopy. Although macro-luminescence of the investigated structures consist of broad emission lines the micro-photoluminescence experiments performed with the spatial resolution of 0.25 μm revealed sharp emission lines from the individual quantum dot in the energy range of 3.20-3.55 eV. It is shown that the magnetic fields up to 7 T do not influence significantly the electronic states of the dots.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 517-521
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and optical properties of boron nitride grown by MOVPE
Autorzy:
Dąbrowska, A.
Pakuła, K.
Bożek, R.
Rousset, J.
Ziółkowska, D.
Gołasa, K.
Korona, K.
Wysmołek, A.
Stępniewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1160531.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Gh
78.30.Fs
78.20.-e
Opis:
Boron nitride layers were grown on sapphire substrate by metal organic vapor phase epitaxy system that was originally designed for growth of GaN. Structures were characterized by scanning electron microscopy, atomic force microscopy, the Raman spectroscopy, absorption and time resolved photoluminescence. Presented results confirm successful deposition of BN layers and gives information about basic properties of the material. The Raman line at 1370 cm^{-1} and absorption edges at 5.6-5.9 eV were observed which is related to hexagonal phase.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-129-A-131
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Localization Effects in GaN/AlGaN Quantum Well - Photoluminescence Studies
Autorzy:
Chwalisz, B.
Wysmołek, A.
Bożek, R.
Korona, K. P.
Stępniewski, R.
Knap, W.
Pakuła, K.
Baranowski, J. M.
Grandjean, N.
Massies, J.
Prystawko, P.
Grzegory, I.
Powiązania:
https://bibliotekanauki.pl/articles/2036024.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.20.-r
73.21.-b
74.40.+k
Opis:
Exciton localization in GaN/AlGaN quantum well structures is studied by photoluminescence. An anomalous temperature behavior of the photoluminescence from the quantum well is observed. With increasing temperature the energy position of the excitonic emission line first decreases up to 20 K, then increases, reaching a maximum around 90 K, and then decreases again in the higher temperature range. The observed behavior is discussed in terms of localization at the interface potential fluctuations. It is argued that the temperature activated migration and subsequent release of the excitons from traps that occurs between 20 K and 90 K are responsible for the observed S-like shape of the energy dependence. The obtained results allow a direct characterization of the energy fluctuations present in GaN/AlGaN quantum wells grown by different techniques.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 573-578
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coupling of LO Phonons to Excitons in GaN
Autorzy:
Wysmołek, A.
Łomiak, P.
Baranowski, J. M.
Pakuła, K.
Stępniewski, R.
Korona, K. P.
Grzegory, I.
Boćkowski, M.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/1952430.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
63.20.Mt
71.55.Eq
Opis:
The photoluminescence of homoepitaxial and heteroepitaxial GaN layers is reported. It is shown that the coupling between LO phonons and neutral acceptor bound excitons is much stronger than the coupling between LO phonons and neutral donor bound excitons. In undoped homoepitaxial layer, in spite of that the no-phonon emission due to donor bound excitons is one order of magnitude stronger than the acceptor bound excitons emission, the predominant structure in the LO phonon replica of the excitonic spectrum is related to optical transitions involving acceptor bound excitons. Temperature studies showed that at higher temperature the LO phonon replica is related to free excitons.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 981-984
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Electrical Studies of Graphene Deposited on GaN Nanowires
Autorzy:
Kierdaszuk, J.
Kaźmierczak, P.
Drabińska, A.
Wysmołek, A.
Korona, K.
Kamińska, M.
Pakuła, K.
Pasternak, I.
Krajewska, A.
Żytkiewicz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1195433.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.ue
72.10.Fk
78.67.Wj
72.80.Vp
Opis:
In this paper using scanning electron microscope, contactless microwave electronic transport and the Raman spectroscopy we studied the properties of graphene deposited on GaN nanowires and compared it with the graphene deposited on GaN epilayer. The Raman micro-mapping showed that nanowires locally change the strain and the concentration of carriers in graphene. Additionally we observed that nanowires increase the intensity of the Raman spectra by more than one order of magnitude.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1087-1089
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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