Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 14

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Optical Properties of GaN Epilayers grown by Gas Source Molecular Beam Epitaxy on AlN Buffer Layer on (111) Si

100%
Godlewski M., Bergman J., Monemar B., Rossner U., Barski A.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
789-792
EN
Optical properties of GaN/AlN/Si (111) epilayers grown by MBE are studied. The observed decay transients of excitonic emissions and their temperature dependence is explained by an efficient transfer link between bound and free excitons.
2
Content available remote

Influence of Growth Conditions on Optical Properties of ZnCdSe/ZnSe Quantum Wells Grown by Molecular Beam Epitaxy

100%
Godlewski M., Bergman J., Monemar B., Kurtz E., Hommel D.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
785-788
EN
The results of investigations of photoluminescence, time-resolved photoluminescence, photoluminescence kinetics and their temperature dependencies are discussed for two types of ZnCdSe/ZnSe multi quantum well structures - for pseudomorphic and for strain relaxed structure. Densities of 2D localized states and averaged localization energies, as seen by excitons, are determined from the photoluminescence kinetics measurements. We show distinct differences between exciton properties in two multi quantum well structures studied.
3
Content available remote

Fermi-Edge Singularity in Luminescence Spectra of P-Type Modulation Doped AlGaAs/GaAs Quantum Wells

86%
Bugajski M., Godlewski M., Regiński K., Holtz P., Bergman J., Monemar B.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
265-270
EN
We have studied an enhancement of the oscillator strength for optical transitions near the Fermi energy in p-type modulation-doped quantum wells, which, so far, deserved much less attention than analogous n-type systems, because of the complicated valence band structure involved. The relatively wide (L=150 Å) quantum wells and high doping levels were used, containing more than one occupied subband. The enhancement in the photoluminescence intensity at the Fermi energy resulted from the strong correlation and multiple scattering of holes near the Fermi edge by the localized electrons.
4
Content available remote

Comparison of Exciton Properties in Quantum Well Structures of ZnCdSe/ZnSe and ZnSe/ZnMgSSe

86%
Godlewski M., Ivanov V., Bergman J., Monemar B., Leonardi K., Behringer M., Hommel D.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
313-316
EN
Properties of excitons in quantum well structures of ZnCdSe/ZnSe and ZnSe/ZnMgSSe are compared. In ternary ZnCdSe quantum wells and at low temperature excitons are strongly localised. Weaker localization is observed in quantum well structures of ZnSe/ZnMgSSe. Present studies suggest formation of negatively charged excitons in the latter structures.
5
Content available remote

Inter-Island Energy Transfer in AlGaAs/GaAs Quantum Wells Grown by Molecular Beam Epitaxy

86%
Godlewski M., Holz P., Bergman J., Monemar B., Regiński K., Bugajski M.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
1007-1011
EN
The results of photoluminescence, time-resolved photoluminescence, photoluminescence excitation and photoluminescence kinetics studies are presented for a Al_{0.3}Ga_{0.7}As/GaAs quantum well system grown without growth interruptions at the interfaces. The time-resolved photoluminescence measurements show drift of excitons towards lower energy states induced in a quantum well by potential fluctuations. We present also a first direct evidence for migration of free excitons from the 24 to 25 ML regions of the quantum well and interpret these results within a linear rate model, deriving the transition rate of 290 ps^{-1}. Such inter-island migration processes have been observed till now only in growth interrupted structures.
6
Content available remote

Comparison of Optical Properties of CdTe/CdMnTe Quantum Wells Grown by Molecular Beam and Atomic Layer Epitaxy

86%
Godlewski M., Kopalko K., Wojtowicz T., Karczewski G., Kossut J., Bergman J., Monemar B.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
1012-1016
EN
Optical properties of a series of CdTe/CdMnTe multi quantum well structures grown with MBE and ALE (CdTe quantum wells only) methods are compared. Based on the results of the photoluminescence experiments we conclude that the ALE growth leads to a different lateral scale of quantum well width fluctuations, which results in different exciton properties in two multi quantum well systems studied. In the wells grown with ALE method excitons are less localized. They can migrate in a quantum well plane between quantum well regions varying in thickness by 1 monolayer.
7
Content available remote

Luminescence Dynamics of Exciton Replicas in Homoepitaxial GaN Layers

86%
Korona K., Baranowski J., Pakuła K., Monemar B., Bergman J., Grzegory I., Porowski S.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
841-844
EN
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.
8
Content available remote

Exciton Properties in CdTe/CdMnTe Quantum Well Structures with Strong Localization Effects

86%
Godlewski M., Narkowicz R., Wojtowicz T., Karczewski G., Kossut J., Bergman J., Monemar B.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
317-320
EN
Strong localization effects present in quantum well structures of CdTe/ CdMnTe noticeably affect exciton dynamics and strength and character of exciton-phonon interaction. We show that the temperature dependences of the PL linewidth, PL peak wavelength and PL decay time strongly deviate from those expected for Wannier-excitons in structures with atomically smooth interfaces.
9
Content available remote

Photoluminescence Studies of Cubic Phase GaN Grown by Molecular Beam Epitaxy on (001) Silicon Covered with Sic Layer

86%
Godlewski M., Ivanov V., Bergman J., Monemar B., Barski A., Langer R.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
777-780
EN
In this work we evaluate optical properties of cubic phase GaN epilayers grown on top of (001) silicon substrate prepared by a new process. Prior to the growth Si substrate was annealed at 1300-1400°C in propane. The so-prepared substrate is covered with a thin (≈ 4 nm) SiC wafer, which allowed a successful growth of good morphological quality cubic phase GaN epilayers. The present results confirm recent suggestion on smaller ionization energies of acceptors in cubic phase GaN epilayers.
10
Content available remote

Optical Characterization of CdZnSe/ZnSe Multiquantum Well System

86%
Godlewski M., Karpińska K., Bergman J., Monemar B., Kurtz E., Hommel D.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 1
209-212
EN
Optical properties of Cd_{x}Zn_{1-x}Se/ZnSe (x = 0.12) multiquantum well system are discussed. The transient photoluminescence and optically de­tected cyclotron resonance experiments demonstrate a strong contribution of bound exciton emission to the low temperature photoluminescence spec­tra.
11
Content available remote

Nonradiative Recombination Processes in (CdTe,CdCrTe)/CdMgTe Quantum Well Structures

73%
Godlewski M., Ivanovi V., Zakrzewski A., Wojtowicz T., Karczewski G., Kossut J., Bergman J., Monemar B.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 4
781-784
EN
Photoluminescence transitions in (CdTe,CdCrTe)/CdMgTe structure grown by molecular beam epitaxy are studied. Photoluminescence investigations show a very strong reduction of the photoluminescence intensity from chromium doped quantum wells. We explain this fact by a very efficient nonradiative recombination in the chromium-doped quantum wells. The present results indicate that the Auger-type energy transfer from excitons to chromium ions is responsible for the photoluminescence deactivation. The efficiency of this process is evaluated.
12
Content available remote

AlGaN Quantum Well Heterostructures for Mid-Ultraviolet Emitters with Improved Room Temperature Quantum Efficiency

73%
Shevchenko E., Toropov A., Nechaev D., Jmerik V., Shubina T., Ivanov S., Yagovkina M., Pozina G., Bergman J., Monemar B.
|
|
vol. 126
|
issue 5
1140-1142
EN
We report on optical studies of exciton localization and recombination kinetics in two single 2.2 nm thick Al_{x}Ga_{1-x}N/Al_{x+0.1}Ga_{0.9-x}N quantum well structures (x=0.55 and 0.6) grown by plasma assisted molecular beam epitaxy on a c-sapphire substrate. Strong localization potential inherent for both the quantum well and barrier regions results in merging of the quantum well and barrier emission spectra into a single broad line centered at 285 nm (x=0.55) and 275 nm (x=0.6). Time-resolved photoluminescence measurements revealed surprising temperature stability of the photoluminescence decay time constant ( ≈ 400 ps) relevant to the recombination of the quantum well localized excitons. This observation implies nearly constant quantum efficiency of the quantum well emission in the whole range from 4.6 to 300 K.
13
Content available remote

Mechanisms of Yellow and Red Photoluminescence in Wurtzite and Cubic GaN

73%
Godlewski M., Suski T., Grzegory I., Porowski S., Langer R., Barski A., Bergman J., Monemar B., Goldys E., Phillips M.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
326-330
EN
The origin of two "deep" photoluminescence (PL) emissions observed in wurtzite (yellow PL) and cubic (red PL) GaN is discussed. PL and time-resolved PL studies confirm donor-acceptor pair character of the yellow band in wurtzite GaN and point to participation of shallow donors in this emission. A similar PL mechanism is proposed for the red emission of cubic GaN. We further show a puzzling property of both yellow and red PLs. Both yellow and red emissions show spatial homogeneity and are only weakly dependent on surface morphology.
14
Publication available in full text mode
Content available

Microwave-Induced Delocalization of Excitons in Ternary Compounds of II-VI and III-V Semiconductors

59%
Ivanov V., Godlewski M., Khachapuridze A., Yatsunenko S., Wojtowicz T., Karczewski G., Bergman J., Monemar B., Shamirzaev T., Zhuravlev K., Leonardi K., Hommel D.
Acta Physica Polonica A
|
2003
|
vol. 103
|
issue 6
559-566
EN
In this work we employ technique of optically detected cyclotron resonance for evaluation of the role of localization processes in CdTe/CdMnTe and CdMnTe/CdMgTe quantum well structures. From microwave-induced changes of excitonic emissions we evaluate magnitude of potential fluctuations (Stokes shift), correlate optically detected cyclotron resonance results with the results of time-resolved experiments and discuss nature of recombination processes in the limit of a strong localization.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.