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Wyszukujesz frazę "Porowski, S." wg kryterium: Wszystkie pola

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Tytuł:
High Pressure Crystallization of III-V Nitrides
Autorzy:
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/1872352.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.-h
Opis:
Crystal growth from the solution under high N$\text{}_{2}$ pressure (HNP method) results in high quality mm size crystals of GaN in 5 to 24 hour process. The crystallization of AlN is less efficient due to relatively lower solubility of nitrogen in the liquid Al. Possibility of InN growth is strongly limited since this compound is unstable at T > 600°C even at 20 kbar. The growth of cm size high quality GaN crystals requires lower supersaturations and longer processes.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 295-302
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Electric Field on Recombination Dynamics of Quantum Confined Carriers
Autorzy:
Korona, K. P.
Borysiuk, J.
Skierbiszewski, C.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2047384.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.47.+p
72.20.Jv
78.55.Cr
Opis:
We present time-resolved photoluminescence measurements of GaN/AlGaN low dimensional structures showing very characteristic changes of dynamics related to strong electric field. Strong piezoelectric and spontaneous polarizations built-in in nitride structures lead to the changes in spatial separation of carriers which leads to changes in recombination energies and radiative lifetimes of the carriers. The observed effect can be well described by a simple exponential relation. The observed dependence can be explained by an approximated model of quantum-confined Stark effect based on the Airy functions.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 243-247
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Application of High Pressure in Physics and Technology of III-V Nitrides
Autorzy:
Grzegory, I.
Leszczyński, M.
Krukowski, S.
Perlin, P.
Suski, T.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2030388.pdf
Data publikacji:
2001-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.-h
78.66.Fd
73.61.Ey
82.60.Lf
78.55.Cr
Opis:
Due to high bonding energy of N$\text{}_{2}$ molecule, the III-V semiconducting nitrides, especially GaN and InN require high N$\text{}_{2}$ pressure to be stable at high temperatures necessary for growth of high quality single crystals. Physical properties of GaN-Ga(l)-N$\text{}_{2}$ system are discussed in the paper. On the basis of the experimental equilibrium p-T-x data and the quantum-mechanical modeling of interaction of N$\text{}_{2}$ molecule with liquid Ga surface, the conditions for crystallization of GaN were established. The crystals obtained under high pressure are of the best structural quality, having dislocation density as low as 10-100 cm$\text{}^{-2}$ which is several orders of magnitude better than in any other crystals of GaN. The method allows to grow both n-type substrate crystals for optoelectronics and highly resistive crystals for electronic applications. The physical properties of the pressure grown GaN measured to characterize both point defects and extended defects in the crystal lattice are discussed in the paper. A special attention is paid to the application of high pressure to reveal the nature of the point defects in the crystals and electric fields in GaN-based quantum structures. Due to their very high structural quality, the pressure grown crystals are excellent substrates for epitaxial growth of quantum structures. It opens new possibilities for optoelectronic devices, especially short wavelength high power lasers and efficient UV light emitting diodes. This is due to the strong reduction in dislocation densities in relation to existing structures (10$\text{}^{6}$-10$\text{}^{8}$ cm$\text{}^{-2}$) which are grown on strongly mismatched sapphire and SiC substrates. The experimental results on the epitaxial growth and physical properties of GaN-based device structures supporting above conclusions are discussed in the paper. The current development of blue laser technology in High Pressure Research Center is shortly reviewed.
Źródło:
Acta Physica Polonica A; 2001, 100, Supplement; 57-109
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Magnetic Anisotropy in Bulk GaMnN:Mg Crystals
Autorzy:
Gosk, J.
Zając, M.
Kamińska, M.
Twardowski, A.
Grzegory, I.
Boćkowski, M.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2036861.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
75.30.Gw
75.50.Pp
Opis:
Magnetic properties of bulk wurtzite n-type GaMnN and highly resistive GaMnN:Mg monocrystals were studied for the magnetic field applied parallel and perpendicular to the crystal hexagonal c-axis. Magnetization of both types of samples reveals paramagnetic behavior. However, for n-type GaMnN isotropic magnetization was observed which is in agreement with Mn d$\text{}^{5}$ configuration. On the other hand, GaMnN co-doped with Mg shows large magnetic anisotropy which suggests Mn to be in nonspherical d$\text{}^{4}$ or d$\text{}^{3}$ configuration.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 665-669
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Pressure Freeze-out of Electrons in Undoped GaN Crystal. Proof of Existence of Resonant Donor State (Nitrogen Vacancy)
Autorzy:
Perlin, P.
Teisseyre, H.
Suski, T.
Leszczyński, M.
Grzegory, I.
Jun, J.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/1931916.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.-i
71.55.Eq
Opis:
We investigated free carriers related optical absorption in GaN in hydrostatic pressures up to 30 GPa. The disappearance of this absorption at pressures close to 18 GPa was explained by trapping electrons resulting from the shift of nitrogen vacancy related donor level into the GaN energy gap at high pressure. We estimated the energetic position of this level at atmospheric pressure to be about 0.8 eV above the conduction band minimum.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 141-143
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:
Crystallographic Properties of Bulk GaN Crystals Grown at High Pressure
Autorzy:
Leszczyński, M.
Grzegory, I.
Bockowski, M.
Jun, J.
Porowski, S.
Jasiński, J.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/1933847.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Dd
61.50.Cj
Opis:
Gallium nitride bulk crystals grown at about 15 kbar and 1500 K have been examined by using the high resolution X-ray diffractometry. An analysis of a set of the rocking curves of various Bragg reflections enabled us to estimate a dislocation density. For the crystals of dimensions lower than about 1 mm it is lower than 10$\text{}^{-5}$ cm$\text{}^{-2}$. For bigger samples the crystallographic quality worsens. With an application of the reciprocal lattice mapping we could distinguish between internal strains and mosaicity which are both present in these crystals The results for the bulk crystals are compared with those for epitaxial layers.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 799-802
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mn Impurity in GaN Studied by Electron Paramagnetic Resonance
Autorzy:
Wołoś, A.
Palczewska, M.
Wilamowski, Z.
Kamińska, M.
Twardowski, A.
Boćkowski, M.
Grzegory, I.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2036027.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.-i
71.55.Eq
71.70.Gm
Opis:
We present the results of electron paramagnetic resonance investigations of GaN bulk crystals doped with Mn. The EPR experiment shows the Mn$\text{}^{2+}$ resonance in all the investigated n-type crystals, while in highly resistive samples extra doped with Mg acceptor the Mn$\text{}^{2+}$ resonance decreases. This is a consequence of the location of Mn acceptor level in GaN band gap. The analysis of the spin relaxation times reveals the Korringa scattering as the dominating spin relaxation mechanism in n-type GaN:Mn crystals. The effective exchange constant determined from spin relaxation rate temperature dependence is of the order of 14 meV.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 595-600
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:
III-V Semiconducting Nitrides Energy Gap under Pressure
Autorzy:
Perlin, P.
Gorczyca, I.
Teisseyre, H.
Suski, T.
Litwin-Staszewska, E.
Porowski, S.
Grzegory, I.
Christensen, N. E.
Powiązania:
https://bibliotekanauki.pl/articles/1921585.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.25.Tn
Opis:
In this paper we present overview of our recent experimental and theoretical results concerning electronic band structure of III-V nitrides under pressure. It is shown here that the pressure coefficients of the direct gap for studied nitrides are surprisingly small. To describe tendency in changes of the gap with pressure we use a simple empirical relation.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 674-676
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 28

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