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2 Acta Physica Polonica A

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Influence of Growth Conditions and Doping on Physical Properties of Gallium Antimonide Single Crystals

100%

Mirowska A. , Orłowski W.

nr 6

1111-1114

Gallium antimonide (GaSb) single crystals were grown by modified Czochralski method integrated with in situ synthesis in a flowing atmosphere of pure hydrogen. The influence of charge material purity as well as other technological parameters on GaSb crystals quality was investigated. High purity undoped GaSb single crystals were grown with residual acceptors concentration < 1.4 × 10^{17} cm^{-3} and high mobility ≈ 690 cm^2/Vs (at 300 K). P-type GaSb crystals were doped with silicon (carrier concentration up to 2 × 10^{19} cm^{-3}) and with zinc (up to 1 × 10^{19} cm^{-3}). Tellurium doped n-type GaSb single crystals were obtained with concentration up to 2 × 10^{18} cm^{-3}. Electrical parameters were investigated by the Hall measurements (300 K and 77 K). Temperature dependent Hall measurements (10 ÷ 300 K) were used to compare the quality of undoped GaSb (obtained from Sb of different purity). Dopant concentration was estimated by glow discharge mass spectroscopy analysis. Axial and radial distribution of carrier concentration were investigated especially for Te-doped crystals (low segregation coefficient of Te in GaSb). Great contribution of compensation and self-compensation mechanisms is shown especially for the beginning part of grown crystals and for low Te-doping level. Radial distribution of physical properties for crystals grown in 〈100〉 direction is not axisymmetrical especially for doped GaSb crystals.

Infrared Spectroscopy of GaAs Doped with Mn

51%

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

nr 5

845-849

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.

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

51%

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

Acta Physica Polonica A

2011

tom 120

nr 5

950-953

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.