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1
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Nonlinear Coupling of Oscillatory Modes in Current Flow in Semi-Insulating GaAs

100%
Karpińska K., Łusakowski J.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 3
425-428
EN
Spontaneous current oscillations in semi-insulating (SI) GaAs sample caused by high electric field domains nucleation were perturbed by modulated illumination. Coupling between domain and photocurrent oscillations leads to quasiperiodic and frequency-locked behaviour. The observed Arnol'd tongues structure follows the Farey tree ordering and agrees with predictions of the circle map theory. We also suggest a possible mechanism responsible for the coupling of the modes.
2
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Current-Voltage Characteristic of Semi-Insulating GaAs, with Trap-Filling Effect

100%
Karpińska K., Łusakowski J.
Acta Physica Polonica A
|
1991
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vol. 79
|
issue 2-3
281-285
EN
A detailed investigation of current-voltage (I- V)characteristics of semi-insulating GaAs sample was performed in the vicinity of room temperature. The sample with 300 K resistivity of 2 x 10^{7} Ω cm was supplied with guard-ring electrodes which allowed the elimination of surface currents. The observed characteristics started with an ohmic part which was followed by a superlinear current on voltage dependence. At a threshold voltage V_{t}h which corresponds to the electric field of about 2 kV/cm the current increased abruptly by a few orders of magnitude. The value of V_{t}h increased with the temperature. It is proposed that the observed shape of the I-V curve is caused by the filling of the EL2 level with injected electrons heated by the electric field.
3
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Hot Carrier Effects in Optically Detected Cyclotron Resonance Studies of III-V Semiconductors

81%
Karpińska K., Dedulewicz S., Godlewski M.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 4
623-626
EN
The mechanisms of irregular photoluminescence intensity oscillations, as observed in optically detected cyclotron resonance experiments, are discussed. Two possible scenarios are analyzed, both requiring impact ionization of the center(s) by electric field accelerated free carriers. The first assumes coexistence of dielectric and energy relaxation processes. The second assumes a subsequent impact ionization of two different centers.
4
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Optical Properties of Molecular Beam Epitaxy Grown ZnSe on GaAs

81%
Karpińska K., Suchocki A., Godlewski M., Hommel D.
Acta Physica Polonica A
|
1993
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vol. 84
|
issue 3
551-554
EN
Photoluminescence studies of molecular beam epitaxy grown ZnSe-on-GaAs layers are presented. The high sensitivity of the PL technique allowed for identification unintentional dopants in pure ZnSe sample. Characteristic photoluminescence lines due to extended defects were observed. The experimental results obtained show a correlation between intentional doping level and extended defects concentration. We conclude also that even though molecular beam epitaxy layers are grown at low temperature, the self-compensation mechanism may still be important. For heavily doped sample edge emission is deactivated likely due to efficient energy transfer link with deep donor-acceptor pair bands.
5
Content available remote

Rare-Earth Excitation Mechanism in Wide Band Gap H-VI Compounds

71%
Karpińska K., Świątek K., Godlewski M., Niinistö L., Leskelä M.
Acta Physica Polonica A
|
1993
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vol. 84
|
issue 5
959-962
EN
The excitation mechanism of rare-earth emission in Eu and Ce doped CaS and SrS is studied. It is proposed that the Eu and probably also Ce emission is induced by the photoionization transition of the rare-earth ion, which is followed by the carrier trapping via the excited state of the ion. At increased temperatures the efficiency of excitation is reduced. We explain this effect by the carrier emission from the excited core state of the rare-earth ion to the continuum of the conduction (valence) band states. It is also suggested that the charge transfer state of the rare-earth ion may act as the intermediate state in the carrier trapping.
6
Content available remote

AlGaAs to GaAs Energy Transfer Mechanisms in AlGaAs/GaAs Structures

71%
Karpińska K., Godlewski M., Żytkiewicz Z., Chen W., Weber E.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 4
713-716
EN
The results of photoluminescence and optically detected cyclotron resonance experiments are presented for thick AlGaAs epilayers grown by liquid phase electroepitaxy method on GaAs:Cr substrate. These results indicate an efficient energy transfer from excited AlGaAs to GaAs.
7
Content available remote

Excitation and Recombination Processes in InAs_{x}P_{1-x}:Yb (x=0.04, 0.07 and 0.11)

71%
Godlewski M., Kozanecki A., Karpińska K., Bergman J. P., Monemar B.
Acta Physica Polonica A
|
1995
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vol. 87
|
issue 1
217-220
EN
Excitation and recombination mechanisms of Yb^{3+} 4f-4f intra-shell emission in InP and InAsP (4, 7 and 11% of As) are analyzed.
8
Content available remote

Optical Characterization of CdZnSe/ZnSe Multiquantum Well System

61%
Godlewski M., Karpińska K., Bergman J., Monemar B., Kurtz E., Hommel D.
Acta Physica Polonica A
|
1995
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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.
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