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1
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GaN Synthesis by Ammonothermal Method

100%
Dwiliński R., Wysmołek A., Baranowski J., Kamińska M., Doradziński R., Garczyński J., Sierzputowski L., Jacobs H.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
833-836
EN
It is shown that ammonothermal method can be successfully used to synthesize GaN powder of good crystallographic quality from ammonia solution at high pressure and a moderate temperature. The size of obtained GaN powder grains was of a few micrometers. The improvement of the powder crystalline quality (examined by X-ray rocking curve, scanning electron microscopy and luminescence measurements) with increasing molar proportion of mineralizer was observed. It was therefore possible to conclude that high molar proportion of mineralizer in ammonia solution plays a crucial role in the polycrystal growth process. Visible luminescence of high efficiency from the GaN powder was found.
2
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Effect of Interface on the Spinodal Decomposition of GaInPAs Solid Solutions during Liquid Phase Heteroepitaxy

100%
Olchowik J.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
812-816
EN
The area of thermodynamical instability in non-ideal solutions appears below a critical temperature. On exceeding this temperature, the excessive energy of the solution takes positive values. It means that the repulsive forces acting between solution elements begin to dominate which leads to the spinodal decomposition. In the present paper, the effect of interatomic interactions on the limits of spinodal decomposition of substitutional solutions of Ga-In-P-As compounds was examined. The influence of the interface energy on the nature of spinodal decomposition was also analysed within the approximation of the coherent coupling of phases during heteroepitaxy from the liquid phase. It was demonstrated that the energy of elastic deformation of the interface lattice markedly changed conditions of the thermodynamical equilibrium.
3
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Morphological Instability of Substrates of A^{III}B^{V} Compounds during Heteroepitaxy from Liquid Phase

100%
Olchowik J., Szymczuk D.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
317-320
EN
The morphological instability of the phase boundary often appears during exposure of the multicomponent liquid phase of A^{III}B^{V} compounds and the binary substrates. The deviation from the thermodynamic equilibrium of the heterosystem at the stage of the "liquid-solid" contact during het­eroepitaxy of A^{III}B^{V} compounds can lead in numerous instances to the so-called catastrophic erosion of the substrates. Catastrophic erosion of the solid phase surface manifests itself in selective etching (reaching considerable depth beneath the surface) or even in complete melting of the substrate dur­ing contact with liquid solution. The analysis of the energy balance at the exposure border of initially saturated liquid phase and the particular binary substrate enables to define the driving force of this effect. In the present paper, there are presented the results of analysis of the erosion processes in the Ga-In-P-As/InP system.
4
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Stimulation of Crystalline Lattice Stabilization of Ga-In-P-As Layers during Heteroepitaxy

100%
Olchowik J.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
477-481
EN
Every process of heteroepitaxial synthesis from liquid phase of A^{III}B^{V} compounds is based on the contact of saturated solution with the binary substrate. The initial difference in the crystalline lattice parameters or in the radii of mutually substituting atoms of the interface causes the shift of the thermodynamic balance point of the system. The change in the total energy of the system connected with this effect causes the deviation of the actual composition of the crystallising solution with respect to the planed one. In the present paper there are shown the results of the theoretical and experimental analysis of the effect of InP substrates on parameters of the Ga_{x}In_{1-x}P_{y}As_{1-y} layer crystallised from liquid phase.
5
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On GaN Crystallization by Ammonothermal Method

100%
Dwiliński R., Baranowski J., Kamińska M., Doradziński R., Garczyński J., Sierzputowski L.
Acta Physica Polonica A
|
1996
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vol. 90
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issue 4
763-766
EN
GaN crystals are grown using ammonothermal method at pressures below 5 kbar and temperatures below 550°C. In this method, GaN is synthesised from high purity metallic gallium. The main role in the low temperature GaN crystallization is played by the chemically active and dense ammonia and dissolved mineralizer. Morphology of the obtained crystals as well as solubility experiments prove that gallium nitride is dissolved and crystallised from solution. Physical properties of GaN crystals obtained using ammonothermal method depend on the growth conditions and the type of mineralizer. All GaN samples reveal very intensive photoluminescence, also at room temperature. The spectra of crystals grown with lithium compound mineralizer are shifted towards higher energies in comparison to crystals grown with potassium based mineralizer. At helium temperatures, phosphorescence is also observed.
6
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Some Optical and Epr Properties of Strain-Free GaN Crystals Obtained by Ammono Method

100%
Dwiliński R., Baranowski J. M., Kamińska M., Doradziński R., Garczyński J., Sierzputowski L., Palczewska M.
Acta Physica Polonica A
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1997
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vol. 92
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issue 4
737-741
EN
AMMONO GaN is grown spontaneously from ammonia solution in form of regular, well shaped, few micrometer crystals. Photoluminescence spectra of these crystals are characterized by fixed positions of very narrow exciton lines (FWHM down to 1 meV), where free excitons A, B, C, resolved two donor bound excitons and acceptor bound exciton are visible. Fixed position of exciton lines is in contrast to small changes of line energies which have been always observed for epitaxial GaN layers because of strain present in them. Free electron concentration of AMMONO GaN is less than few times 10^{15} cm^{-3}, as estimated from EPR signal of shallow donor. The above-mentioned facts qualified these crystals as state of the art strain-free, model material for basic parameter measurements of GaN. In this work, results of PL and EPR measurements performed on AMMONO GaN crystals are presented and discussed.
7
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On the High Compositional Uniformity of Thick GaAlAs Layers Grown by Liquid Phase Electroepitaxy

63%
Żytkiewicz Z., Miotkowska S.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
765-768
EN
The results of electroepitaxial growth of thick GaAlAs layers on GaAs substrates are presented. It is experimentally proven that effective convective mixing of the solution volume results in the compositional uniformity of GaAlAs layers, even in spite of the high compositional non-uniformity of the material supplying the solutes (Al, As) to the solution during the growth of the layers. For the first time this allowed us to grow uniform GaAlAs layers with thicknesses up to 200-300 μm in a wide composition range from a small (5 g) amount of solution.
8
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In Situ Monitoring of Electroepitaxial Growth of Thick AlGaAs Layers

63%
Żytkiewicz Z.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
777-780
EN
In situ growth monitoring technique has been used to analyse growth disturbances during the liquid phase electroepitaxial growth of thick AlGaAs layers. It allowed us to explain the nature of growth instability occurring at the end of the growth and affecting the maximum thickness of AlGaAs layers obtainable by liquid phase electroepitaxy.
9
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Electroepitaxial Growth of GaSb and AlGaSb Thick Epitaxial Layers

63%
Zytkiewicz Z. R., Dobosz D.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
965-968
EN
Semi-bulk epitaxial layers of GaSb and AlGaSb up to 3 and 1 mm thick, respectively, were successfully grown by the liquid phase electroepitaxy on GaSb substrates. The growth procedure allowed us to achieve high crystallographic perfection as well as compositional uniformity of ternary layers.
10
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Study on Species of Heavy Lanthanides(III) Chelates Extracted into Organic Phase with 5,7-Dichloro-8-hydroxyquinoline

63%
Czakis-Sulikowska D., Malinowska A., Pustelnik N., Kuźnik B.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
427-430
EN
The nature of species formed in the extraction of lanthanides Ln(III) (where Ln = Tb, Dy, Ho, Er, Tm and Yb) with 5,7-dichloro-8-hydro xyquinoline (HL) in CHCl_{3} from water or water-methanol phase was examined. It was stated that during the extraction from water phase the chelates LnL_{3} (Tb, Tm), seven-coordinated self-adducts LnL_{3} ÷ HL (Er, Ho) or both types of these species (Dy, Yb) were extracted. In the presence of methanol (MeOH) in the aqueous phase the eight-coordinated mixed species of the type LnL_{3}·2MeOH were observed.
11
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Anisotropic Magnetic Properties of URhIn₅ Compound

51%
Bartha A., Kratochvílová M., Sechovský V., Custers J., Dušek M.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
339-341
EN
We report on synthesis and anisotropic physical properties of URhIn₅. High quality single crystals were grown from In self-flux. The compound undergoes a second-order phase transition into an antiferromagnetic state at T_{N} = 98 K. The transition is magnetic field independent up to 9 T. An increase of the resistivity ρ with j along the [100], [110] and [001] tetragonal axis indicates a spin-density-wave induced order with the gap opening first along the [001] direction. The magnetic susceptibility χ = M/H exhibits a strong anisotropy. Above T= 200 K, χ(T) follows the Curie-Weiss law with the effective moment of μ_{eff} = 3.71 μ_{B}/U and the Weiss temperatures of θ_{P}^{[100]} = -900 K and θ_{P}^{[001]} = -500 K for H ∥ [100] and H ∥ [001], respectively. The characteristic Kondo-like temperature for URhIn₅ yields T_{K}= 125 K.
12
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Synchrotron Topographic Studies of Domain Structure in Czochralski Grown Pr_xLa_{1-x}AlO_3 and Pr_xLa_{1-x-y}Mg_yAlO_3 Crystals

51%
Wieteska K., Wierzchowski W., Malinowska A., Turczyński S., Lefeld-Sosnowska M., Pawlak D., Łukasiewicz T., Paulmann C.
Acta Physica Polonica A
|
2012
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vol. 121
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issue 4
910-914
EN
A domain structure and crystallographic defects in Czochralski grown single crystals of Pr_xLa_{1-x}AlO_3 and Pr_xLa_{1-x-y}Mg_yAlO_3 were characterised with a number of methods including conventional and synchrotron X-ray diffraction topography, and polariscopic micrography. The observed twin domain systems were located perpendicularly to 〈100〉_{pcub} and 〈110〉_{pcub} (pseudocubic) directions. It has been confirmed that the domains are of the same orientation and a twin character as those described in literature for LaAlO_3 and LaGaO_3 crystals. The use of section transmission topography enabled to indicate that the domains are perpendicular to the (100)_{pcub} surface of the samples. The misorientation of lattice in the domains was evaluated from the white beam topographs and a tendency of its increase with increasing concentration of praseodymium was revealed.
13
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Fabrication and Optical Characterization of CdSe Thin Films Grown by Chemical Bath Deposition

51%
Kariper İ., Bağlayan Ö., Göde F.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2B
B-219-B-221
EN
Cadmium selenide thin films with different pH values (pH = 10, 11, 12 and 13) are produced on glass substrates at 50°C for 3 h by chemical bath deposition technique. The structural, morphological and optical properties of the films are characterized by X-ray diffraction, scanning electron microscopy and optical absorption spectroscopy, respectively. The obtained films have hexagonal structure. The optical transparency of the films varies between 85% and 98% at wavelength of λ = 550 nm. The scanning electron microscopy studies show that the film deposited at pH = 10 exhibits the formation of nanorods in the width range from 1.8 μm to 10.9 μm and length range from 20.0 μm to 85.5 μm. The optical properties of the films are determined by measuring transmittance and absorbance characteristics which are used to find the optical band gap energy, refractive index, extinction coefficient and real dielectric constant. The band gap width of the films increases from 1.70 eV to 2.30 eV with increasing pH values. The refractive index of the film at pH = 10 is found as 1.54.
14
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Optical Characterization of ZnO Nanorods Grown by the Ultra-Fast and Low Temperature Hydrothermal Process

51%
Witkowski B., Ivanov V., Wachnicki Ł., Gierałtowska S., Godlewski M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 5
1199-1201
EN
The results of photoluminescence investigations of zinc oxide nanorods are reported. These nanorods grown on undoped silicon substrates were obtained by low temperature and ultra-fast version of a microwave-assisted hydrothermal method. The photoluminescence investigations show very high quality of the obtained material. From photoluminescence studies we conclude the lack of carrier localization effects. The photoluminescence is dominated by band gap edge emission of bound excitonic (donor bound excitons) origin. Thus, the photoluminescence quenching observed at increased temperatures is associated with thermal ionization of shallow donors. From photoluminescence analysis (changes of photoluminescence line width) a strength of exciton-acoustic phonon coupling is evaluated.
15
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Solution Growth and Investigation of the Single Crystals from the CePdIn System

51%
Kratochvílová M., Custers J., Sechovský V.
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vol. 126
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issue 1
324-325
EN
We report on the investigation of recently discovered heavy fermion compounds within the Ce-Pd-In system. Single crystals of Ce_{n}Pd_{m}In_{3n+2m} (n=2, 3, 5; m=1, 2) and Ce_{4}Pd_{10}In_{21} were synthesized from In-flux. Specific heat measurements of the multiphase Ce_{n}Pd_{m}In_{3n+2m} system revealed a superconducting transition at T_{c}=0.69 K arising from Ce_{2}PdIn_{8} and another, magnetic transition at T_{m}=1.67 K arising from either Ce_{3}PdIn_{11} or Ce_{5}Pd_{2}In_{19}. Low-temperature data of Ce_{4}Pd_{10}In_{21} display ferromagnetic long-range order below 0.8 K.
16
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Seed Production and Melt Replenishment for the Czochralski Growth of Silicon Germanium

51%
Armour N., Dost S.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
198-212
EN
The silicon transport in a silicon-germanium melt has been studied to address the issues of melt replenishment and seed production for the Czochralski growth of silicon germanium (SiGe) crystals. The growth of SiGe single crystals by the Czochralski method requires that the melt be replenished with silicon during the growth process due to the rejection of germanium into the melt during solidification. To facilitate the replenishment of the melt, an accurate knowledge of the dissolution rate of silicon into the melt and its transport through the melt is required. To address these issues, a number of experiments have been carried out on the dissolution of silicon into a germanium melt. Liquid phase diffusion growth experiments were also conducted for insight into transport and as a possible method for seed crystal production. The experiments encompassed various temperatures, crucible geometries, crucible translation, and magnetic field levels to determine optimum conditions for the most favorable dissolution rates and mass transport in the melt. Results have shown that replenishment from bottom of the crucible is most effective due to the enhanced silicon transport by buoyancy. The application of magnetic fields may also provide an effective mean to control the replenishment rate (mass transport rate) in the melt.
17
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Development of Crystal Growth Technique of Silicon by the Czochralski Method

51%
Kakimoto K.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
227-230
EN
We report on the Czochralski method for single silicon crystal growth and discuss heat and mass transfer and defect formation in the crystal. A reflector was used for separation of the heating and cooling areas in the furnace enabling us to speed up crystal growth. The melt flow to stabilize the temperature distribution in a crucible was controlled using transverse magnetic fields in a large-scale silicon Czochralski furnace. The setup allows for changes in important parameters of point defect formation to be made, such as vacancies and interstitials, by changing temperature and flow fields in the furnace. A numerical calculation was developed to predict the tendency for growth of a vacancy rich or interstitial rich crystal by estimating the value of the ratio between the growth rate and temperature gradient in the crystals.
18
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Growth and Characterization of Non-Linear Optical Single Crystal: L-cysteine Hydrochloride Monohydrate

51%
Azeezaa V., Arul Pragasam A., Sunitha T., Koteeswari P., Suresh S.
Acta Physica Polonica A
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2015
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vol. 128
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issue 3
423-430
EN
Nonlinear optical single crystals of L-cysteine hydrochloride monohydrate (LCB) were grown by slow evaporation technique. Single crystal X-ray diffraction analysis revealed the crystal system and helped to determine lattice parameter values. Powder X-ray diffraction analyses were carried out and the diffraction patterns were indexed. The optical properties of the crystals were determined using UV-visible spectroscopy. Optical constants such as refractive index, extinction coefficient and electric susceptibility were determined from UV-visible spectroscopy. The Fourier transform infrared studies confirmed the various functional groups present in the grown crystal. The mechanical behaviour of the grown crystals was studied using Vicker's microhardness tester. The thermal analysis confirmed that the crystal was stable up to 108.7°C. The dielectric constant and the dielectric loss measurements were carried out for different temperatures and frequencies. Second harmonic generation of LCB crystal was investigated by the Kurtz powder technique.
19
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X-ray Topographic Investigations of Domain Structure in Czochralski Grown Pr_{x}La_{1-x}AlO_{3} Crystals

51%
Wieteska K., Wierzchowski W., Malinowska A., Turczyński S., Lefeld-Sosnowska M., Pawlak D., Łukasiewicz T., Graeff W.
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issue 2
268-271
EN
In the present paper X-ray diffraction topographic techniques were applied to a number of samples cut from Czochralski grown Pr_{x}La_{1-x}AlO_{3} crystals with different ratio of praseodymium and lanthanum. Conventional and synchrotron X-ray topographic investigations revealed differently developed domain structures dependent on the composition of mixed praseodymium lanthanum aluminium perovskites. Some large mosaic blocks were observed together with the domains. In the best crystals, X-ray topographs revealed striation fringes and individual dislocations inside large domains. Synchrotron topographs allowed us to indicate that the domains correspond to three different crystallographic planes, and to evaluate the lattice misorientation between domains in the range of 20-50 arc min.
20
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Supercrystallization of NaCl from Solution Irradiated by Soft X-Rays

51%
Janavičius A., Purlys R., Rinkūnas R.
Acta Physica Polonica A
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2013
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vol. 123
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issue 4
777-781
EN
It was found that irradiation of a water solution of NaCl with the diffractometer DRON3-M (Russian device) had a large influence on two-step processes of crystallization. The irradiation in the first stage of crystallization of the solution produces metastable radicals of water and excited seeds, which stimulate a very fast crystallization after switching off irradiation. After the crystals reach a sufficient size, the crystal growth can be explained by creation of vacancy-interstitial pairs in the growing crystal due to irradiation. The increase of linear dimensions of the growing irradiated crystals is proportional to the square root √t of crystallization time because most important place in crystallization takes the ions diffusion by irradiated vacancies.
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