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1
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On the Tunneling Among Shallow and Deep Centers in ZnS

100%
Zakrzewski A., Sienkiewicz A.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
251-254
EN
Results of the photo-ESR studies of recharging processes due to tunneling in ZnS:Cu crystals are presented. It was found that the tunneling among shallow and deep centers seems to be a second order effect in the overall photoluminescence quenching in ZnS by transition metal impurities.
2
Content available remote

On the Symmetry of the Sulfur Pair-Related Defect in Silicon

81%
Bennebroek M., Zakrzewski A., Frens A., Schmidt J.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
725-728
EN
A sulfur-related-pair defect in silicon has been studied with optically detected magnetic resonance spectroscopy. Measurement of the angular dependence of the optically detected magnetic resonance signals supplemented by the analysis of the spectrum "quality" yield to the conclusion that the point group symmetry of the defect studied is C_{1h}.
3
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Photo-ESR Studies of Ni doped ZnS and ZnSe

81%
Surma M., Zakrzewski A., Godlewski M., Surkova T.
Acta Physica Polonica A
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1995
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vol. 87
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issue 1
221-224
EN
The results of electron spin resonance experiments are presented for nickel doped ZnS and ZnSe. Energy level position of Ni^{1+} state in band gap of ZnS and ZnSe is determined. The nonradiative recombination processes of donor-acceptor pairs in Ni doped samples are discussed.
4
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Sensitivity of Polarimetric Waveguide Interferometer for Different Wavelengths

81%
Gut K., Zakrzewski A., Pustelny T.
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issue 6
1140-1142
EN
This publication presents experimental measurement methodology which allows to determine the characteristics of sensitivity planar differential interferometer. To confirm data reliability additional measurements were done such as simulations in OptiBPM software by Optiwave. Curves received from two methods: experimental and theoretical, were summed up and compared. Conclusions were made on their basis, for example the influence of used wavelengths or refractive index of single mode waveguide cladding on curves of sensitivity differential interferometer using planar waveguide received from the ion exchange method.
5
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Self-Induced Persistent Photoconductivity in ZnTe-Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} Heterojunctions

71%
Van Khoi L., Dobrowolski W., Zakrzewski A., Dobaczewski L., Gałązka R.
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EN
At temperatures lower than 200 K the photomemory effect has been observed in ZnTe-Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} heterojunctions. The persistent photoconductivity can be achieved either by illumination from an external light source or by a self-absorption of the electroluminescence radiation when a voltage of about 10 V for a few seconds is applied to the diode. Current-voltage characteristics are of the form I~ V^{m}. The capacitance and electroluminescence measurements show that the photomemory effect in ZnTe-Cd_{1-x}Mn_{x} Te_{1-y}Se_{y} heterojunctions can be caused by the bistable nature of the In dopant in the Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} substrate. In the high resistivity interface layer and the substrate material indium forms centers similar to DX-like centers in Zn_{x}Cd_{1-x}Te and Cd_{1-x}Mn_{x}Te.
6
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Co^{2+} Ions in ZnS_{x}Se_{1-x}:Co - ESR and Optical Studies

62%
Świątek K., Surkova T., Sienkiewicz A., Zakrzewski A., Godlewski M., Giriat W.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
593-596
EN
The electron spin resonance of Co^{2+} ions in ZnS_{x}Se_{1-x}:Co mixed crystals was measured at temperature of 3 K and microwave frequency of 9.47 GHz. Trigonal Co_{Zn}^{2+}-S center in the ZnS_{0.001}Se_{0.999}:Co crystal was identified and parameters of relevant spin Hamiltonian were determined. Influence of alloy disorder in the anion sublattice on the Co_{Zn}^{2+} ground and first excited states is briefly discussed.
7
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Spatial Correlations of Donor Charges in MBE CdTe

52%
Suski T., Wiśniewski P., Litwin-Staszewska E., Wasik D., Przybytek J., Baj M., Karczewski G., Wojtowicz T., Zakrzewski A., Kossut J.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
929-932
EN
We present experimental evidence that at high pressures indium donors in CdTe localize electrons in spatially correlated manner. We have studied Hall mobility, μ_{H}, as a function of electron concentration, n_{H}, at T=77 K. Changes of n_{H} have been achieved by two methods. High pressure freeze-out of electrons onto localized states of In-donors leads to the mobility enhancement with respect to the situation when n_{H} has been modified by means of a subsequent annealing of the sample. As a result, depending on the degree of spatial correlations in the impurity charges arrangement, different values of μ_{H} correspond to the same value of n_{H}. The variation of mobility with electron concentration suggests that the localized state of In-donor represents likely negatively charged DX state.
8
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Nonradiative Recombination Processes in (CdTe,CdCrTe)/CdMgTe Quantum Well Structures

52%
Godlewski M., Ivanovi V., Zakrzewski A., Wojtowicz T., Karczewski G., Kossut J., Bergman J., Monemar B.
Acta Physica Polonica A
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1997
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vol. 92
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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.
9
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Lattice Parameter Relaxation during MBE of ZnTe/Cd_{1-x}Zn_{x}Te/Cd_{0.5}Zn_{0.5}Te Buffer Layers by RHLED and HRTEM

52%
Kret S., Karczewski G., Zakrzewski A., Dłużewski P., Dubon A., Wojtowicz T., Kossut J., Delamarre C., Laval J. Y.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
795-798
EN
The dynamics of the lattice relaxation processes were investigated us­ing a reflection of a high energy electron diffraction analysis system dur­ing growth by molecular beam epitaxy of ZnTe/Cd_{1-x}Ζn_{x}Te/Cd_{0.5}Mn_{0.5}Te buffers on GaAs substrates. The variation of the lattice parameter recorded by the high energy electron diffraction during the growth was later confirmed by an analysis of high resolution transmission electron microscopy images. We report also on an observation of oscillations of the lattice parameter during the deposition of several first layers of ZnTe on CdTe.
10
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Transmission Second Harmonic Generation in Cd_{1-x}Mn_{x}Te at 1.064 µm

52%
Koziarska B., Kowalczyk L., Suchocki A., Wojtowicz T., Zakrzewski A., Karczewski G., Janik E., Kossut J.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
423-426
EN
Second harmonic generation, created by nanosecond Nd : YAG laser pulses at 1.064 µm with relatively low intensity in Cd_{1-x}Mn_{x}Te bulk crystals and thin layers was measured in transmission geometry. The effect practically occurs in a very thin surface layer of the material and it is used as a rela­tively straightforward method of layer quality characterization. It is shown that the angular dependence of the second harmonic generation intensity in thin layers of CdTe with good crystallographic (and optical) quality agrees very well with the theory in contrary to the samples with some distortions from the ideal structure which exhibits large distortions from the theory.
11
Content available remote

Cubic MnTe - Growth by Molecular Beam Epitaxy and Basic Structural Characterization

52%
Zakrzewski A., Janik E., Dynowska E., Leszczyński M., Kutrowski M., Wojtowicz T., Karczewski G., Bąk-Misiuk J., Domagała J., Kossut J.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
433-436
EN
We report on growth by molecular beam epitaxy of thick layers of MnTe with zinc blende structure. Films as thick as 5.6 µm were obtained. Char­acterization by X-ray diffraction proved their good structural quality. We determined the lattice constant and its temperature dependence. Broad lu­minescence due to internal Mn^{2+}- transitions was observed. It showed an unexpected temperature dependence.
12
Content available remote

Two-Electron DX State in CdTe:In

52%
Skierbiszewski C., Wiśniewski P., Litwin-Staszewska E., Suski T., Wilamowski Z., Zakrzewski A., Karczewski G., Jantsch W.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
927-930
EN
In this paper we investigate electron emission/capture from/to the DX state of indium in CdTe by means of high pressure freeze-out cycle and steady-state photo-conductivity experiments. The results indicate that the DX state is occupied by two electrons. A comparison with deep level transient spectroscopy data shows that two-electron emission occurs at low temperatures, while one-electron emission takes place at high temperatures.
13
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Indium Doping of CdTe Grown by Molecular Beam Epitaxy

52%
Karczewski G., Zakrzewski A., Kutrowski M., Jaroszyński J., Dobrowolski W., Grodzicka E., Janik E., Wojtowicz T., Kossut J., Barcz A.
Acta Physica Polonica A
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1995
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vol. 87
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issue 1
241-244
EN
We report on n-type indium doping of CdTe films grown by molecular beam epitaxy on (001) GaAs substrates. By adjusting the flux of In atoms we can precisely control the carrier concentration over three orders of magnitude - from 8 × 10^{14} up to 1.3 × 10^{18} cm^{-3}. In agreement with earlier reports we confirmed that Cd overpressure plays an important role in the doping process. The doping appears to be most effective for Cd/Te pressure ratio of 1.5. For this value of Cd/Te pressure ratio essentially 100% efficiency of doping is achieved at low In concentrations (< 10^{18} cm^{-3}). At higher In concentrations acceptor impurities compensate shallow donors limiting the concentration of free carriers.
14
Content available remote

Schottky Junctions Based on the ALD-ZnO Thin Films for Electronic Applications

42%
Krajewski T., Luka G., Smertenko P., Zakrzewski A., Dybko K., Jakiela R., Wachnicki L., Gieraltowska S., Witkowski B., Godlewski M., Guziewicz E.
Acta Physica Polonica A
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2011
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vol. 120
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issue 6A
A-17-A-21
EN
The ZnO-based Schottky diodes revealing a high rectification ratio may be used in many electronic devices. This paper demonstrates several approaches to obtain a ZnO-based Schottky junction with a high rectification ratio. The authors tested several methods such as: post-growth annealing of the ZnO layer, acceptor (nitrogen) doping, as well as the ZnO surface coating with a properly chosen dielectric material. The influence of these approaches on the diode's rectification ratio together with modeling based on the differential approach and thermionic emission theory are presented.
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