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


Wyświetlanie 1-11 z 11
Tytuł:
Built-In Electric Field in High Quality GaN/AlGaN Quantum Wells
Autorzy:
Zieleniewski, K.
Pakuła, K.
Bożek, R.
Masztalerz, K.
Wysmołek, A.
Stępniewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2048083.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.67.De
77.55.hn
81.15.Gh
Opis:
We report studies on electric field built in GaN/Al$\text{}_{0.09}$Ga$\text{}_{0.91}$N structure of nominally 6 nm wide quantum well. The sample was grown in horizontal metal-organic chemical vapor deposition reactor using innovative technology that decreases the density of screw dislocations. Firstly, using visible and mid infra-red interference pattern along the sample, the layer thickness and consequently the quantum well width was determined to vary linearly with the position. Secondly, photoluminescence spectra was taken at different positions. Correlation of those two measurements allows us to determine the built-in electric field to be 0.66 MV/cm, which is considerably larger than previously reported for similar structures.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 657-659
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Optical and Electrical Properties of High Temperature Annealed Heteroepitaxial GaN:Mg Layers
Autorzy:
Wojdak, M.
Baranowski, J. M.
Suchanek, B.
Pakuła, K.
Jun, J.
Suski, T.
Powiązania:
https://bibliotekanauki.pl/articles/1968449.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Fd
73.61.Ey
78.55.Cr
Opis:
In this paper we present for the first time luminescence and electrical measurements of GaN:Mg heteroepitaxial layers annealed at very high temperatures up to 1500°C and at high pressures of nitrogen up to 16 kbar. The presence of high nitrogen pressure prevents GaN from thermal decomposition. It was found that annealing in the presence of additional Mg atmosphere leads to a high quality p-type epitaxial layer of the hole concentration equal to 2×10$\text{}^{17}$ cm$\text{}^{-3}$ and mobility 16 cm$\text{}^{2}$/(V s). However, annealing at high temperatures without additional magnesium causes conversion to n-type. It is also shown that in the high temperature annealed GaN:Mg epilayers the donor-acceptor luminescence is the dominant recombination channel.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 1059-1062
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:
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:
Luminescence Dynamics of Exciton Replicas in Homoepitaxial GaN Layers
Autorzy:
Korona, K. P.
Baranowski, J. M.
Pakuła, K.
Monemar, B.
Bergman, J. P.
Grzegory, I.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/1968240.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.-y
78.47.+p
78.55.Cr
Opis:
Photoluminescence of excitons and their phonon replicas in homoepitaxial MOCVD-grown gallium nitride (GaN) layers have been studied by picosecond (ps) time-resolved photoluminescence spectroscopy. The time-resolved photoluminescence spectroscopy has shown that the free excitons and their replicas have the fastest dynamics (decay time of about 100 ps). Then, the excitons-bound-to-donors emission rises (with the rise time similar to the free excitons decay time) and decays with t=300 ps. The excitons-bound-to-acceptors has the slowest decay (about 500 ps). It has been found that the ratio of excitons-bound-to-acceptors and excitons-bound-to-donors amplitudes and their decay times are different for 1-LO replicas and then for zero-phonon lines, whereas the ratio of amplitudes and the decay time of the 2-LO replicas are similar to the ones of the zero-phonon lines.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 841-844
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:
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:
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
    Wyświetlanie 1-11 z 11

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