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Infrared Spectroscopy of Light Impurities in GaSb

100%
Kaczor P., Kaliński Z., Jakieła R.
Acta Physica Polonica A
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2005
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vol. 108
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issue 4
711-715
EN
In our work we study the doping behaviour of sulphur in Czochralski grown GaSb by means of the high resolution Fourier transform infrared spectroscopy and the secondary ion mass spectroscopy. We have revealed that the sulphur impurity forms an effective mass like donor state bound to the L-minimum of the conduction band. From the far infrared spectrum of this donor we derive the effective band masses of the L band minimum. We also observe local vibrational modes related to the arsenic and phosphorus isoelectronic impurities. From the nearest neighbour isotope splittings of these modes we conclude that the arsenic impurity occupies a tetrahedral substitutional site and the phosphorus impurity - a low symmetry lattice site.
2
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Cathodoluminescence Measurements at Liquid Helium Temperature of Poly- and Monocrystalline ZnO Films

88%
Witkowski B., Wachnicki Ł., Jakieła R., Guziewicz E., Godlewski M.
Acta Physica Polonica A
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2011
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vol. 120
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issue 6A
A-28-A-30
EN
Scanning electron microscopy, cathodoluminescence and secondary ion mass spectroscopy investigations are used to study an inter-link between structural quality, elements distribution and light emission properties of ZnO poly- and monocrystalline films grown by the atomic layer deposition. Cathodoluminescence and scanning electron microscopy investigations were performed at liquid helium temperature for four different types of ZnO films deposited on different substrates.
3
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Ti-Al-N MAX Phase a Candidate for Ohmic Contacts to n-GaN

76%
Borysiewicz M., Kamińska E., Piotrowska A., Pasternak I., Jakieła R., Dynowska E.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1061-1066
EN
Fabrication of a Ti₂AlN MAX phase for contact applications to GaN-based devices is reported. Sample characterisation was done by means of X-ray diffraction and secondary ion mass spectroscopy. Successful Ti₂AlN monocrystalline growth was observed on GaN and Al₂O₃ substrates by annealing sputter-deposited Ti, Al and TiN layers in Ar flow at 600°C. The phase was not seen to grow when the layers were deposited on Si (111) or when the first layer on the substrate was TiN. N-type GaN samples with Ti₂AlN layers showed ohmic behaviour with contact resistivities in the range 10¯⁴ Ωcm².
4
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Structural and Electrical Properties of SiC Grown by PVT Method in the Presence of the Cerium Vapor

76%
Avdonin A., Racka K., Tymicki E., Grasza K., Jakieła R., Pisarek M., Dobrowolski W.
Acta Physica Polonica A
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2013
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vol. 124
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issue 5
761-764
EN
The results of investigation of structural and electrical properties of bulk SiC crystals, which were grown by physical vapor transport method with different Ce impurity content added to the SiC source material, are presented. The gradual dosage of cerium from the SiC source and continuous presence of the cerium vapor over the SiC crystallization fronts during the crystal growth processes are confirmed. The cerium influences the overall concentration of structural defects. The increase of the concentration of both, donors and acceptors, and appearance of new shallow donors (15-32 meV) in 4H-SiC crystals are observed.
5
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Substrates Grown from the Vapor for ZnO Homoepitaxy

76%
Skupiński P., Kopalko K., Łusakowska E., Domukhovski V., Jakieła R., Mycielski A., Grasza K.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1361-1368
EN
The novel method of preparation of epi-ready ZnO substrates is demonstrated. The substrates were made of unique ZnO crystals grown by chemical vapor transport method using hydrogen as the transport agent. The effect of low-level doping (Mn, Co, Cu, and V) on the structural quality of the crystals was investigated. Atomic layer deposition was used to verify usability of the substrates for homoepitaxy. The thermal annealing prior to the atomic layer deposition process and effect of thermal annealing of the epitaxial layers was studied. The X-ray diffraction and atomic force microscopy methods were applied to study the structural quality of the ZnO layers. Detection of the dopants in the substrates by secondary ion mass spectroscopy made possible the measurement of the thickness of the layers. The obtained root mean square roughness for both the substrates and layers ranged between 0.2 nm and 5 nm, and was dependent on the sample crystallographic orientation and sequence of polishing and annealing procedures. The optimal recipe for the epi-ready substrate preparation was formulated.
6
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Response of ZnO/GaN Heterostructure to Ion Irradiation

64%
Barcz A., Pągowska K., Kozubal M., Guziewicz E., Borysiewicz M., Dyczewski J., Jakieła R., Ratajczak J., Snigurenko D., Dynowska E.
Acta Physica Polonica A
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2015
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vol. 128
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issue 5
832-835
EN
In this paper we report on the analysis of Al⁺-implanted ZnO/GaN bilayers in search for the damage production mechanism and possible ion mixing. 100 nm or 200 nm thick ZnO epitaxial layers were grown on GaN substrates by either sputter deposition or atomic layer deposition technique followed by adequate annealing. Ion irradiations of ZnO/GaN were carried out at room temperature using 200 keV Al⁺ ions with fluences of 2×10¹⁵ and 10¹⁶ at./cm². Unprocessed and irradiated samples were characterized by the Rutherford backscattering spectrometry in channeling geometry (RBS\c), X-ray diffraction and transmission electron microscopy. Additionally, secondary ion mass spectrometry was employed for the aforementioned samples as well as for the implanted samples subjected to further annealing. It was found that the damage distributions in ZnO/GaN differ considerably from the corresponding defect profiles in the bulk ZnO and GaN crystals, most probably due to an additional strain originating from the lattice mismatch. Amount of intermixing appears to be relatively small; apparently, efficient recombination prevents foreign atoms to relocate to large distances.
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ZnO Thin Films Deposited on Sapphire by High Vacuum High Temperature Sputtering

64%
Borysiewicz M., Pasternak I., Dynowska E., Jakieła R., Kolkovski V., Dużyńska A., Kamińska E., Piotrowska A.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
686-688
EN
ZnO (0001) layers on sapphire (0001) substrates were fabricated by means of high temperature high vacuum magnetron sputtering. The layers were deposited onto a thin MgO buffer and a low temperature ZnO nucleation layer, which is a technology commonly used in MBE ZnO growth. This paper reports on using this technology in the sputtering regime.
8
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Atomic Force Microscopy Study of a Voltage Effect on CdZnTe Crystal Dimensions

64%
Aleszkiewicz P., Wojciechowski T., Fronc K., Kolkovsky V., Janik E., Jakieła R., Mycielski A., Karczewski G., Aleszkiewicz M.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1041-1047
EN
In this work we studied the influence of an external electric voltage on spatial dimensions of CdZnTe mixed crystals. In order to get an absolute magnitude of the sample thickness and to gain insight to the changes of lateral dimension, in quasi-bulk 3 μm thick CdZnTe layers grown by molecular beam epitaxy square craters were formed by ion sputtering in a secondary ion mass spectrometer. The vertical and lateral dimensions of the craters were studied by the atomic force microscopy. The atomic force microscopy measurement revealed that the thickness of the CdZnTe layer increases in a result of applying a single voltage pulse to the sample surface and decreases reversibly after applying reversely biased voltage. The voltage triggering was high enough to switch the conductivity state of the sample i.e., the effect of thickness change is accompanied by the effect of conductivity switching. The thickness change is significant, reaching several percents of the entire layer thickness.
9
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XANES Studies of Mn K and L_{3,2} Edges in the (Ga,Mn)As Layers Modified, by High Temperature Annealing

64%
Wolska A., Lawniczak-Jablonska K., Klepka M., Jakieła R., Demchenko I., Sadowski J., Holub-Krappe E., Persson A., Arvanitis D.
Acta Physica Polonica A
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2008
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vol. 114
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issue 2
357-366
EN
Ga_{1-x}Mn_xAs is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper Ga_{1-x}Mn_xAs samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scattering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not observe changes in the electronic structure of Ga and As introduced by the presence of the Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate the preferred interstitial positions of the Mn atoms.
10
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Ferromagnetism of Narrow-Gap Ge_{1-x-y}Sn_xMn_yTe and Layered In_{1-x}Mn_xSe Semiconductors

52%
Lashkarev G., Sichkovskyi V., Radchenko M., Dmitriev A., Slyn'ko V., Slyn'ko E., Kovalyuk Z., Butorin P., Knoff W., Story T., Szymczak R., Jakieła R., Aleshkevych P., Dobrowolski W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1219-1227
EN
Magnetic susceptibility, Hall effect and resistivity of narrow-gap Ge_{1-x-y}Sn_xMn_yTe single crystals (x = 0.083÷0.115; y = 0.025÷0.124) were investigated in the temperature range 4.2-300 K revealing a ferromagnetic ordering at T_C ≈ 50 K. Temperature dependence of magnetization indicates a superparamagnetic phase with magnetic clusters arranging in a spin glass state below the freezing temperature T_f. Magnetic structure of InSe ⟨Mn⟩ 2D-ferromagnetic single crystals was studied by SQUID magnetometry, neutron diffraction, secondary ion mass spectroscopy, and wave dispersive spectra. Hysteresis loops of magnetization were observed at least up to 350 K. The cluster model of ferromagnetism is considered. The formation of self-assembled superlattice ferromagnetic InSe:Mn/antiferromagnetic MnSe during growth process and further annealing was established.
11
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ZnCoO Films Obtained at Low Temperature by Atomic Layer Deposition Using Organic Zinc and Cobalt Precursors

52%
Łukasiewicz M., Wójcik-Głodowska A., Guziewicz E., Jakieła R., Krajewski T., Łusakowska E., Paszkowicz W., Minikayev R., Kiecana M., Sawicki M., Godlewski M., Wachnicki Ł., Szczepanik A.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1235-1240
EN
In this paper we report on ZnCoO thin films grown by atomic layer deposition method in reactor F-120 Satellite. ZnCoO films were grown at low temperature (T_s=160°C) with a new zinc precursor (dimethylzinc - DMZn) and with cobalt (II) acetyloacetonate (Co(acac)₂) as a cobalt precursor and deionized water as an oxygen precursor. In this paper we concentrate on the methods of homogenizing Co distribution in ZnCoO films.
12
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Do We Understand Magnetic Properties of ZnMnO?

52%
Godlewski M., Wójcik A., Kopalko K., Ivanov V., Wilamowski Z., Jakieła R., Guziewicz E., Szczepanik A., Dłużewski P., Chikoidze E., Barjon J., Dumont Y., Putkonen M., Niinistö L., Tang D.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
261-267
EN
Optical and magnetic properties of ZnMnO films are discussed based on the results of cathodoluminescence, photoluminescence, and magneto-photoluminescence investigations. We show that photoluminescence/cathodoluminescence emissions are strongly quenched and become in-plane inhomogeneous in samples with increased Mn fractions. Strong polarization of photoluminescence is observed, even though excitonic lines do not shift and are not split at magnetic fields up to 6 T.
13
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Ferromagnetic Transition in Ge_{1-x}Mn_{x}Te Layers

52%
Knoff W., Domukhovski V., Dybko K., Dziawa P., Jakieła R., Łusakowska E., Reszka A., Świątek K., Taliashvili B., Story T., Szałowski K., Balcerzak T.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
904-906
EN
Ferromagnetic transition temperature in thin layers of diluted magnetic (semimagnetic) semiconductor Ge_{1-x}Mn_{x}Te was studied experimentally by SQUID magnetometry method and analyzed theoretically for a model Ising-type diluted magnetic system with Ruderman-Kittel-Kasuya-Yosida indirect exchange interaction. The key features of the experimentally observed dependence of the Curie temperature on Mn content (x ≤ 0.12) and conducting hole concentration p = (1-10) × 10^{21} cm^{-3} were reproduced theoretically for realistic valence band and crystal lattice parameters of p-Ge_{1-x}Mn_{x}Te taking into account short carrier mean free path encountered in this material and Ruderman-Kittel-Kasuya-Yosida mechanism with both delta-like and diffused character of spatial dependence of the exchange coupling between magnetic ions and free carriers.
14
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ZnCoO Films by Atomic Layer Deposition - Influence of a Growth Temperature οn Uniformity of Cobalt Distribution

52%
Łukasiewicz M., Witkowski B., Godlewski M., Guziewicz E., Sawicki M., Paszkowicz W., Łusakowska E., Jakieła R., Krajewski T., Kowalik I., Kowalski B.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
921-923
EN
We report on the structural, electrical and magnetic properties of ZnCoO thin films grown by atomic layer deposition method using reactive organic precursors of zinc and cobalt. As a zinc precursor we applied either dimethylzinc or diethylzinc and cobalt(II) acetyloacetonate as a cobalt precursor. The use of these precursors allowed us the significant reduction of a growth temperature to 300°C and below, which proved to be very important for the growth of uniform films of ZnCoO. Structural, electrical and magnetic properties of the obtained ZnCoO layers will be discussed based on the results of secondary ion mass spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, atomic force microscopy, Hall effect and SQUID investigations.
15
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Magnetic Properties of Epitaxial (Ge,Mn)Te Thin Films with Varying Crystal Stoichiometry

52%
Knoff W., Domukhovski V., Dybko K., Dziawa P., Górska M., Jakieła R., Łusakowska E., Taliashvili B., Story T., Reszka A., Anderson J., Rotundu C.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1159-1165
EN
Magnetization of 1 μm thick ferromagnetic IV-VI (Ge, Mn)Te semiconductor layers with 10 at.% of Mn was studied by SQUID magnetometry method up to the magnetic fields of 70 kOe. The layers were grown on BaF₂ (111) substrates by molecular beam epitaxy with varying Te molecular flux, which permitted the control of layer stoichiometry and conducting hole concentration. X-ray diffraction and in situ electron diffraction characterization of layer growth and crystal structure revealed two-dimensional mode of growth and monocrystalline rhombohedral crystal structure of (Ge, Mn)Te layers. Controlling the layer stoichiometry influences the temperature dependence of magnetization with the ferromagnetic Curie temperature varying in Ge_{0.9}Mn_{0.1}Te layers from T_c=30 K (low Te flux) to T_c=42 K (high Te flux).
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