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1

X-Ray High-Resolution Diffraction and Transmission Topography Study of InGaAs Grown by Liquid Encapsulated Czochralski Technique

100%

Kowalski G., Gronkowski J., Borowski J., Hruban A.

Acta Physica Polonica A

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2008

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vol. 114

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issue 2

391-398

EN

New results on ternary InGaAs crystals grown using liquid encapsulated Czochralski technique with constant liquid composition are reported. X-ray high-resolution diffractometry (rocking curves and reciprocal space maps) as well as X-ray topography using the transmission Lang setup were used. Growth history of the bulk ingots was revealed.

2

Observation of Superconductivity in Highly Cr-Doped GaP Single Crystals

76%

Gosk J., Strzelecka G., Kowalski G., Hruban A., Kamińska M., Twardowski A., Gronkowski J.

Acta Physica Polonica A

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2006

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vol. 110

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issue 2

189-193

EN

Studying bulk GaP, highly doped with Cr, and searching for possible ferromagnetic semiconductor in view of spintronic applications, we found superconducting behavior of this material unexpectedly. Magnetization techniques and X-ray diffraction were applied to study these crystals. Magnetization revealed superconducting features up to about 6 K and X-ray studies showed that superconductivity might be related to small size Cr precipitates.

3

Mn Impurity in Bulk GaAs Crystals

64%

Pawłowski M., Piersa M., Wołoś A., Palczewska M., Strzelecka G., Hruban A., Gosk J., Kamińska M., Twardowski A.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

825-830

EN

Magnetic and electron transport properties of GaAs:Mn crystals grown by Czochralski method were studied. Electron spin resonance showed the presence of Mn acceptor A in two charge states: singly ionized A^- in the form of Mn^{2+}(d^5), and neutral A^0 in the form of Mn^{2+}(d^5) plus a bound hole (h). It was possible to determine the relative concentration of both types of centers from intensity of the corresponding electron spin resonance lines. Magnetization measured as a function of magnetic field (up to 6 T) in the temperature range of 2-300 K revealed overall paramagnetic behavior of the samples. Effective spin was found to be about 1.5 value, which was consistent with the presence of two types of Mn configurations. In most of the studied samples the dominance of Mn^{2+}(d^5)+h configuration was established and it increased after annealing of native donors. The total value of Mn content was obtained from fitting of magnetization curves with the use of parameters obtained from electron spin resonance. In electron transport, two mechanisms of conductivity were observed: valence band transport dominated above 70 K, and hopping conductivity within Mn impurity band at lower temperatures. From the analysis of the hopping conductivity and using the obtained values of the total Mn content, the effective radius of Mn acceptor in GaAs was estimated as a = 11±3Å.

4

Influence of Chemical Composition of Liquid Phase and Growth Process on Physical Properties of Bi_2Se_3, Bi_2Te_3 and Bi_2Te_2Se Compounds

64%

Hruban A., Materna A., Dalecki W., Strzelecka G., Piersa M., Jurkiewicz-Wegner E., Diduszko R., Romaniec M., Orłowski W.

Acta Physica Polonica A

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2011

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vol. 120

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issue 5

950-953

EN

We studied synthesis and crystal growth of Bi_2Te_3, Bi_2Se_3 and Bi_2Te_2Se compounds by means of vertical Bridgman method. Crystals were grown from stoichiometric melts and under different molar ratio of Bi:Te, Bi:Se or Bi:Te:Se. The obtained crystals were characterized by X-ray diffraction analysis, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, and the Hall effect measurements. Some of the samples demonstrated insulating bulk behavior, by means of resistivity versus temperature measurements.

5

Infrared Spectroscopy of GaAs Doped with Mn

64%

Rutkowska A., Wasik D., Witowski A., Sadowski M., Orłowski W., Strzelecka G., Hruban A., Kamińska M., Twardowski A., Potemski M.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

845-849

EN

We found that the fine structure related to Lyman spectra of [Mn^{2+}(d^5) + a hole] centers in GaAs was present only for samples with low Mn concentration. Such samples, at low temperature, did not show any hopping conductance within Mn impurity band. Magnetooptical measurements revealed that magnetic field induced splitting of the Lyman optical transitions was larger than Zeeman splitting observed for typical shallow acceptors in GaAs, like Be, Zn, and C. This experimental result proved that in the case of Mn acceptor impurity, the exchange coupling of a hole and the S = 5/2 Mn^{2+}(d^5) core could not be neglected, which was in accordance with the [Mn^{2+}(d^5) + a hole] model of the neutral Mn center in GaAs.

6

Formation of Mn-Related Defect Band in InP

52%

Macieja B., Korona K., Piersa M., Witowski A., Wasik D., Wysmołek A., Strzelecka G., Hruban A., Surma B., Palczewska M., Kamińska M., Twardowski A.

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EN

Electron paramagnetic resonance, optical absorption, luminescence and electrical studies of InP highly doped with Mn were performed. Electron paramagnetic resonance revealed presence of manganese in Mn^{2+}(d^5) configuration. In optical absorption, systematic reduction of InP band gap was observed with increase in Mn content. This was correlated with increase in photoionization-type absorption band starting at 0.2 eV. Time-resolved photoluminescence measurements showed decrease in photoexcited carrier lifetime and shortening of donor-acceptor pair recombination time with increase in Mn content. Moreover, photoluminescence band was shifted to lower energies, similarly to optical band gap. In electrical transport two mechanisms of conductivity were observed. Valence band transport dominated at higher temperatures, above 160 K, and activation energy of free-hole concentration was determined as about 0.20 eV. At lower temperatures hopping conductivity, clearly related to Mn defect band, was present. All these results were consistent with assumption of creation of Mn-related defect-band at 0.2 eV above InP valence band. It was found that Mn centers responsible for this band were in configurations of either d^5 or d^5 plus a hole localized about 7Å around corresponding Mn core.

Refine search results

X-Ray High-Resolution Diffraction and Transmission Topography Study of InGaAs Grown by Liquid Encapsulated Czochralski Technique

Observation of Superconductivity in Highly Cr-Doped GaP Single Crystals

Mn Impurity in Bulk GaAs Crystals

Influence of Chemical Composition of Liquid Phase and Growth Process on Physical Properties of Bi_2Se_3, Bi_2Te_3 and Bi_2Te_2Se Compounds

Infrared Spectroscopy of GaAs Doped with Mn

Formation of Mn-Related Defect Band in InP