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1
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Optical Analyses of Si and GaAs Semiconductors by Fractional-Derivative-Spectrum Methods

100%
Rzodkiewicz W., Kulik M., Papis E., Szerling A.
Acta Physica Polonica A
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2009
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vol. 116
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issue S
S-95-S-98
EN
Optical spectra analysis provides a wealth of information on physical properties of various semiconductor materials. Fractional derivative spectrum technique is especially interesting when the limitations of the standard treatment occur. In this paper we present the fractional derivative spectrum method for analysis of the optical spectra for both Si and GaAs. The significant changes in critical point parameters in each treated Si and GaAs samples in comparison to that before treatment have been observed. Our investigation illustrates that fractional derivative spectrum is a very good technique to extract basic information on relevant physical quantities from the observed optical spectra, and it has the advantages of flexibility, directness, and sensitivity, which give possibility to obtain the Van Hove singularities (critical point parameters) efficiently with one consent.
2
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Effects of Ballistic Transport in Wires of n-PbTe

64%
Grabecki G., Wróbel J., Dietl T., Papis E., Kamińska E., Piotrowska A., Ueta Y., Sprinholtz G., Bauer G.
Acta Physica Polonica A
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1997
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vol. 92
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issue 4
789-792
EN
We present results of magnetotransport studies on quantum wires of submicron PbTe epilayers, fabricated by means of electron beam lithography and dry etching. When the wire width is reduced down to 1 μm, the transition from diffusive to ballistic regime is observed. Effects associated with collimation and boundary scattering are found in the Hall, longitudinal, and van der Pauw magnetoresistance for wires and junctions in the shape of a cross.
3
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Conductance Fluctuations in PbSe: Manifestation of Ballistic Transport in Macroscale?

64%
Grabecki G., Takeyama S., Adachi S., Takagi Y., Dietl T., Kamińska E., Piotrowska A., Papis E., Frank N., Bauer G.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
727-730
EN
Precise magnetoresistance measurements on microstructures of photolithographically patterned PbSe epilayers have been performed in the mag­netic field range up to 17 Τ. Unusually large, reproducible magnetoconductance fluctuations have been observed. The fluctuation amplitude decreases exponentially with the magnetic field. A correlation magnetic field of the fluctuations corresponds to the Aharonov-Bohm effect which involves elec­tron trajectories much smaller than the electron mean free path. This points strongly to the ballistic, not diffusive, origin of the observed phenomenon.
4
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THz Time Domain Spectroscopy of Thin Gold Layers on GaAs

64%
Szczytko J., Adomavicius R., Papis E., Barańska A., Wawro A., Krotkus A., Piętka B., Łusakowski J.
Acta Physica Polonica A
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2012
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vol. 122
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issue 6
1118-1120
EN
Thin layers of Au with the thickness of several nanometers were prepared on a semi-insulating GaAs substrate. The layers' thickness was determined by ellipsometry. THz time-domain spectroscopy was applied to determine a complex index of refraction of thin Au layers. The obtained results allow for a more precise modeling of the performance of semiconductor devices at THz frequencies.
5
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Materials Technology for GaSb-Based optoelectronic Devices

64%
Piotrowska A., Kamińska E., Piotrowski T., Piskorski M., Guziewicz M., Papis E., Gołaszewska-Malec K., Kasjuniuk S.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
903-906
EN
A study is made of surface preparation, metallization, patterning and dielectric deposition with the aim of developing process technology for GaSb-based photonic devices.
6
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Quantum Hall Ferromagnet in Magnetically-Doped Quantum Wells

64%
Andrearczyk T., Jaroszyński J., Wróbel J., Karczewski G., Wojtowicz T., Papis E., Kamińska E., Piotrowska A., Popović D., Dietl T.
Acta Physica Polonica A
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2003
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vol. 104
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issue 2
93-102
EN
The article reviews our recent studies on quantum Hall ferromagnetism in diluted magnetic semiconductors. We carried out magnetoresistance studies on modulation-doped, gated heterostructures of (Cd,Mn)Te/(Cd,Mg)Te:I. We put into evidence the formation of Ising quantum Hall ferromagnet with Curie temperature T_C as high as 2 K. Quantum Hall ferromagnetism is manifested by anomalous magnetoresistance maxima. Moreover, magnitude of these spikes depends dramatically on the history of the sample, shows hysteresis when either magnetic field or gate voltage are swept, stretched-exponential time evolution characteristic of glassy systems, and strong Barkhausen noise. Our study suggests that these metastabilities stem from the slow dynamics of ferromagnetic domains.
7
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Mesoscopic Phenomena in Microstructures of IV-VI Epilayers

64%
Grabecki G., Dietl T., Plesiewicz W., Lenard A., Skośkiewicz T., Kamińska E., Piotrowska A., Papis E., Frank N., Bauer G.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
551-554
EN
Magnetoresistance measurements of photolithographically patterned PbSe and Pb-{1-y}Mn_{x}Se microstructures were performed. Reproducible mag­netoconductance fluctuations with the amplitude increasing with decreasing temperature were observed. Unexpectedly, these fluctuations contain a com­ponent periodic in the magnetic field, and their magnitude is greater than that expected from the current theory of the universal conductance fluctua­tions. Possible explanations are discussed.
8
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Dimensional Crossovers in Magnetoresistance of Submicron Films and Wires of CdTe:In

52%
Jaroszyński J., Wróbel J., Sawicki M., Skośkiewicz T., Karczewski G., Wojtowicz T., Kossut J., Dietl T., Kamińska E., Papis E., Piotrowska A., Duś R., Nowakowski R.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
1027-1031
EN
We present millikelvin studies of magnetoresistance for epitaxial films and wires of CdTe:In. In comparison to the data with theoretical predictions for the weakly localized regime we put into the evidence the presence of the temperature-induced dimensional crossovers in the studied systems. Our measurements probe the electron phase-breaking rate and indicate that the main dephasing mechanism arises from electron scattering from thermal fluctuations of three- or two-dimensional electron liquid.
9
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Electrical and Structural Properties of Ohmic Contacts to n-Type and High Resistivity CdTe

52%
Kamińska E., Piotrowska A., Guziewicz M., Gierlotka S., Papis E., Łusakowski J., Szadkowski K., Kwiatkowski S., Dietl T., Grabecki G., Jaroszyński J., Karczewski G., Zakrzewski A. K.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
411-414
EN
The interaction between CdTe and In during the formation of an ohmic contact has been investigated. Emphasis is placed on the study of the effect of thermally induced sublimation of cadmium on electrical properties of con­tacts. Presented results prove the effectiveness of cap annealing and rapid thermal processing in fabrication of improved ohmic contacts with limited Cd losses during the contacting procedure.
10
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Conductance Fluctuations in Quantum Wires of n-CdTe and n-Cd_{1-x}Mn_{x}Te

52%
Jaroszyński J., Wróbel J., Sawicki M., Skośkiewicz T., Karczewski G., Wojtowicz T., Kossut J., Dietl T., Kamińska E., Papis E., Barcz A., Piotrowska A.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
1000-1004
EN
We present millikelvin studies of magnetoconductance in submicron wires of In-doped n^{+}-CdTe and n^{+}-Cd_{0.99}Mn_{0.01}Te epilayers. Weak-field magnetoresistance which arises from quantum localization as well as universal conductance fluctuations have been observed. The exchange coupling to magnetic impurities is shown to decrease the correlation field of the fluctuations. This novel effect is interpreted by invoking a new driving mechanism of the magnetoconductance fluctuations - the redistribution of the electrons between energy levels of the system, induced by the giant s-d spin-splitting of the electronic states.
11
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Conductance Anomalies in Strained Quantum Wires: the Case of PbSe and PbTe

52%
Grabecki G., Wróbel J., Dietl T., Sawicki M., Skośkiewicz T., Papis E., Kamińska E., Piotrowska A., Frank N., Ueta Y., Sprinholtz G., Bauer G.
|
EN
We show that conducting edge channels are formed in free standing wires of PbSe/BaF_{2} and PbTe/BaF_{2} as temperature is lowered. The effect results from spatially inhomogeneous strain caused by a difference between the thermal expansion coefficients of the epilayer and the substrate. The presence of the edge channels can explain anomalous mesoscopic effects observed previously in these wires.
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