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1
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X-Ray Topographic Investigation of Cellular Structure and its Relation to another Defects in Various Types of GaAs Single-Crystals

100%
Wierzchowski W., Mazur K.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
789-794
EN
The defect patterns in GaAs crystal grown using liquid encapsulated Czochralski and gradient freeze methods with various types of doping were characterized using complementary X-ray topographic methods. It was found that the cellular structure occurring in the low doped crystal is developed independently from the actual growth surface. The occurrence of the cellular structure is connected with significant lattice deformation, and some results point that significant stress can influence its formation. The high doping prevents formation of the cellular structure, but at higher doping the phenomenon of "cellular growth" can occur due to instabilities of the growth surface. The present results point that defect pattern in GaAs crystals is more affected by the type of doping than by the choice of the growth method.
2
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Observation of Interference Fringes in Bragg-Case Synchrotron Double-Crystal Images of Stacking Faults in Diamond

100%
Wierzchowski W., Moore M.
Acta Physica Polonica A
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1992
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vol. 82
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issue 2
185-191
EN
Bragg-case synchrotron double-crystal images of stacking faults were studied in a slab prepared from a synthetic diamond of a good quality. The images of stacking faults in topographs taken on the tails of the rocking curve exhibited well pronounced interference fringes. The fringes were strongly dependent on the angular setting and they were less spaced further from the maximum. The experimental images were compared with those theoretically predicted from an application of plane-wave dynamical theory. A reasonably good correspondence between theoretical and experimental images was obtained. The theoretical images of stacking faults were dependent on the type of stacking fault, producing some difference in the first fringe.
3
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The Images of Dislocations in Synchrotron Bragg-Case Section Topography of Diamond

100%
Wierzchowski W., Moore M.
Acta Physica Polonica A
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1992
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vol. 82
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issue 2
193-200
EN
Bragg-case synchrotron section topographs were studied in parallel slabs cut from a synthetic diamond of a good quality. The topographs revealed the Pendellösung fringes and images of dislocations and other defects containing several fringe systems. The experiment provided the opportunity for studying of the theoretical dislocation images obtained by numerical integration of the Takagi-Taupin equations. A program employing a variable step of integration in the Bragg-case has been presented. The influence of the finite slit width and of the limited beam divergence on the theoretical images is also discussed.
4
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Stereoscopic Observation of Synthetic Diamond with Haruta Stereo-Pairs of Synchrotron Transmission Double-Crystal Topographs

81%
Moore M., Lang A. R., Wierzchowski W.
Acta Physica Polonica A
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1994
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vol. 86
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issue 4
613-616
EN
The Haruta method is used for stereoscopic observation of a 1.5 × 4 × 4 mm^{3} cuboctahedral synthetic diamond with transmission double-crystal topography. The experiments were performed using a synchrotron double-crystal arrangement with asymmetrical diamond 220 reflection selecting 1.0 Å radiation. The appropriate Haruta pairs were matched from a series taken with positions on the rocking curve changed by small intervals. A reasonable stereoscopic effect was observed for most defect images, particularly dislocations, stacking faults and growth sector boundaries. It was established that some interference fringes do not produce good stereoscopic effects and appear on the exit surfaces of the diamond.
5
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Lattice Deformation Studies in Silicon Implanted with High-Energy Protons

81%
Wieteska K., Dłużewska K., Wierzchowski W.
Acta Physica Polonica A
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1996
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vol. 89
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issue 3
395-400
EN
The deformation of crystal lattice in silicon implanted with protons of energy 1.6-9 MeV was studied by means of X-ray topography and double-crystal rocking curve measurements. The samples were investigated as-implanted and after thermal and electron annealing. The surface relief of the implanted part of the crystal was also revealed with optical methods. As-implanted wafers exhibited spherical bending being convex at the implanted side. Thermal and electron annealing caused a dramatic increase in bending of the implanted part while the bending of the remaining part of the sample was reduced. A characteristic behaviour of a double-crystal topographic contrast in the annealed crystals was explained due to bending of the shot-through layer along the Gaussian profile.
6
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Synchrotron White Beam Topographic Studies of Gallium Arsenide Crystals

81%
Wierzchowski W., Wieteska K., Graeff W.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
1015-1019
EN
A series of samples cut out from different types of gallium arsenide crystals with low dislocation density were studied by means of white beam synchrotron topography. The investigation was performed with transmission and back-reflection projection methods and transmission section method. Some of the topographs in transmission geometry provided a very high sensitivity suitable for revealing small precipitates. The transmission section images significantly differed depending on the wavelength and absorption. In some cases a distinct Pendellösung fringes and fine details of dislocation and precipitates images were observed. It was possible to reproduce the character of these images by means of numerical simulation based on integration of Takagi-Taupin equations. Due to more convenient choice of radiation, synchrotron back-reflection projection topography provided much better visibility of dislocations than analogous methods realized with conventional X-ray sources.
7
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Interference Fringes in Synchrotron Section Topography of Implanted Silicon with a Very Large Ion Range

81%
Wieteska K., Wierzchowski W., Graeff W., Dłużewska K.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
1021-1024
EN
Silicon crystals implanted with 9 MeV protons to the dose of 5×10^{17} cm^{-2} were studied with X-ray topographic methods using both conventional and synchrotron radiation sources. After the implantation the crystals were thermally and electron annealed. The implantation produced large 600 μm thick shot-through layer while the total thickness of the samples was 1.6 mm. It was confirmed by means of double crystal topography that the whole crystal was elastically bent. The transmission section patterns revealed both parts of the implanted crystal separated by strong contrasts coming from the most damaged layer and distinct interference fringes which appeared on one side of the topograph only. The location of the fringes changed when the beam entered the other side of the sample. The mechanism of fringe formation was studied with numerical integration of the Takagi-Taupin equations, especially studying the intensity distribution in the diffraction plane. The simulations reproduced the location of the fringes in different geometries and indicate that they can be caused both by variable crystal curvature and variable ion dose.
8
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The Simulation of Bragg-Case Section Images οf Dislocations and Inclusions in Aspect of Identification of Defects in SiC Crystals

81%
Balcer T., Wierzchowski W., Wieteska K.
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issue 2
336-340
EN
The numerical simulation has been applied for studying of Bragg-case section topographic images of dislocation and rod-like inclusions. The validity of simple approximation of extinction contrast was confirmed in the case of screw dislocations in silicon carbide crystals. A procedure for approximate calculation of the strain field of rod-like inclusion was constructed, consisting of adding the contributions from a very large number of point-like inclusions uniformly distributed inside the assumed volume of the inclusion. The procedure ensured a reasonable similarity between the simulated topographs and experimental Bragg-case section topographic images of some pipe-formed cavities in silicon carbide crystals. The method is useful for some other materials, e.g. it enabled to compute realistic simulation of plane-wave topographs of the rod-like inclusions in YAG.
9
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White Beam Synchrotron Topographic Characterisation of Silicon Wafers Directly Bonded by Oxide Layer

71%
Wierzchowski W., Wieteska K., Graeff W., Gawlik G., Pawłowska M.
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vol. 96
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issue 2
283-288
EN
Various types of layer structures obtained by direct bonding of oxidised silicon wafers were studied by means of different X-ray topographic methods using white synchrotron beam and the observation of selective etching pattern using scanning electron microscopy and optical microscopy with Nomarski contrast. In the present investigation the particularly important results were obtained with synchrotron section topography, which revealed different defects caused by bonding of thick wafers, in particular the dislocations and microcracks. The different situation was observed in the case of bonding with a very thin layer separated from a silicon substrate by high dose proton implantation. In this case a thin layer accommodated practically all induced strain and the bonded oxidised thick substrate remained defect-free in its inner volume.
10
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Lattice Deformation in Al_{x}Ga_{1-x}As Epitaxial Layers Caused by Implantation with High Doses of 1 Mev Si Ions

71%
Wieteska K., Wierzchowski W., Graeff W., Turos A., Grötzschel R.
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vol. 96
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issue 2
289-293
EN
A series of highly perfect Al_{0.45}Ga_{0.55} As epitaxial layers implanted with 1 MeV Si ions to the doses in a range 7×10^{13}-2×10^{15} ions/cm^{2} were studied with various conventional and synchrotron X-ray diffraction methods. The presently used methods allowed both the measurement of lattice parameter changes and strain induced deformation. The evaluation of complete strain profiles was also performed by numerical simulation of diffraction curves. It was found that the implantation induced considerable change of lattice parameter reached the maximum at the dose 3×10^{14} ions/cm^{2}. The recorded curves proved also that the lattice parameter is almost constant in the near surface region of the implanted layers. The applied doses did not cause lattice amorphisation at room temperature.
11
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Investigation of Misfit Dislocation Sources in GaAs Epitaxial Layers

71%
Wierzchowski W., Mazur K., Strupiński W., Wieteska K., Graeff W.
Acta Physica Polonica A
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1996
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vol. 89
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issue 3
341-346
EN
The formation of misfit dislocation was studied in GaAs homoepitaxial layers on the substrates containing considerable amount of isoelectronic indium. The layers were grown with metal-oxide chemical vapour deposition and chemical vapour deposition methods including low temperature process with tertiarbutylarsine arsenic source. The critical conditions of misfit dislocation formation were exceeded up to 5×. The samples were examined before and after epitaxial process with a number of different X-ray topographic and diffractometric methods, including high resolution synchrotron white beam topography. The crystallographic identification of the defects was supported by the numerical simulation of topographic images. It was found that a number of threading dislocations, continuing in the epitaxial layer from those existing in the substrate, did not take part in the formation of misfit dislocations despite a suitable slip system. On the other hand, the formation of misfit dislocations from small imperfections of epitaxial deposit was proved in many cases. A reasonable good quality of the layers was confirmed by the resolution of individual defects and only small broadening of rocking curves.
12
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Content available

Investigation of Lattice Strains in Layered Structures Containing Porous Silicon

71%
Wierzchowski W., Wieteska K., Graeff W., Brzozowski A., Nossarzewska-Orłowska E.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
283-288
EN
Silicon layered structures containing porous silicon modified with various thermal treatments and epitaxial layers deposited on porous layers were studied with a number of complementary X-ray diffraction methods using synchrotron source. The methods of characterisation included recording of rocking curves for reflections with various asymmetry as well as projection, section and micro-Laue topography. It was found that oxidising and sintering of porous silicon seriously modified the strains in the porous layer and in some cases even inverting the sense of strain with respect to that in initially formed porous layer. Consequently the deposited epitaxial layer usually was not laterally coherent with the substrate. Some of the investigated layers were not stable in time and after few months period exhibited significant lost of coherence of porous skeleton.
13
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Content available

Interference Fringes in the Plane Wave Topographic Images of Growth Bands in Si:Ge

71%
Wieteska K., Wierzchowski W., Graeff W., Lefeld-Sosnowska M., Regulska M.
Acta Physica Polonica A
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2002
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vol. 101
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issue 5
729-734
EN
An Si:Ge crystal with approximately 3% of germanium was studied with strongly collimated short-wavelength monochromatic synchrotron beam (beamline E2 at HASYLAB). The topographs obtained in the asymmetric 224 reflection revealed the presence of interference fringes related to growth bands caused by segregation of germanium. The fringes, observed for the first time, were strongly dependent on the angular setting and it was possible to distinguish at least three systems of fringes. A number of features of the existing strain field, which may be important for the formation of the fringes, was determined using other topographic methods, especially the Bragg-case section topography.
14
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Topographic and Reflectometric Investigation of Crystallographic Defects and Surface Roughness in 4H Silicon Carbide Homoepitaxial Layers Deposited at Various Growth Rates

62%
Wierzchowski W., Wieteska K., Mazur K., Kościewicz K., Balcer T., Strupiński W., Paulmann C.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
915-919
EN
Undoped 4H silicon carbide epitaxial layers were deposited by means of CVD method with growth rates of 2 μm/h, 5 μm/h and 11 μm/h at 1540°C on n-doped 8°, 4° and 0° off-cut 4H-SiC (00·1) substrates. The structural defects were studied before and after growth of the epitaxial layers by means of conventional Lang topography, synchrotron white beam and monochromatic beam topography and by means of X-ray specular reflectometry. The topographic investigations confirmed the continuation of the dislocations in the epitaxial deposit on the 8° and 4° off-cut substrates without new extended defects. The important difference occurred in the surface roughness of the epitaxial layers, which increased for higher growth rates. The epitaxial layers grown on 0° off-cut substrates at analogous condition contained usually other SiC polytypes, but the influence of the growth rate on the distribution of the polytypes was observed.
15
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X-Ray Topographic Studies of Defect Structure in YVO_4 Crystals

62%
Wieteska K., Wierzchowski W., Łukasiewicz T., Wierzbicka E., Malinowska A., Lefeld-Sosnowska M., Graeff W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 2
455-461
EN
The perfection of YVO_4 crystals, which are predicted to replace formerly used YAG garnets due to higher quantum efficiency and lower excitation level, was studied. The investigations of Czochralski grown undoped YVO_4 single crystals were performed mainly by means of X-ray topographic methods. Both synchrotron and conventional X-ray sources were used. The study revealed relatively high density of weak point-like contrasts which can be most probably interpreted as dislocation outcrops. In regions of the crystal close to its boundary we observed glide bands. It was also found that in some regions the dislocations form local subgrain boundaries. The white beam back reflection and monochromatic beam topography allowed to evaluate a local misorientation which not exceeded several angular minutes. No segregation fringes were observed proving a good homogeneity of chemical composition.
16
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Conventional and Synchrotron X-Ray Topography of Defects in the Core Region of SrLaGaO_4

62%
Malinowska A., Lefeld-Sosnowska M., Wieteska K., Wierzchowski W., Pajączkowska A., Graeff W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 2
433-438
EN
SrLaGaO_4 single crystals are perspective substrate materials for high temperature superconductors thin films, elements of thermal radiation receivers and other electronic devices. The defect structure of the Czochralski grown SrLaGaO_4 crystal was investigated by means of X-ray topography exploring both conventional and synchrotron sources. The crystal lattice defects in the core region of the crystal were investigated. The regular network of defects arranged in rows only in ⟨100⟩ direction was observed. Owing to high resolution of synchrotron radiation white beam back reflection topographs one can distinguish individual spots forming the lines of the rows. It can be supposed that these elongated rod-like volume defects are located in 100 lattice planes forming a kind of walls. They are built approximately of the same phase as crystal but crystallize at a different moment than a rest of the crystal due to the constitutional supercooling.
17
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Content available

X-ray Synchrotron Studies of Nanostructure Formation in High Temperature - Pressure Treated Silicon Implanted with Hydrogen

62%
Wieteska K., Wierzchowski W., Graeff W., Misiuk A., Barcz A., Bryja L., Popov V.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
239-244
EN
The effects of various high temperature-pressure treatments in Czochralski grown silicon (Cz-Si) implanted with 130 keV hydrogen to the dose of 4times10^{16} cm^{-2} were investigated using synchrotron X-ray topographic methods and rocking curve measurements. The high temperature- pressure processes included 10 h annealing at 450°C, 650°C, and 725°C at argon pressure 12 kbar and 1 bar. The topographic investigations were performed with projection and section methods in back-reflection and transmission geometry. It was found that annealing resulted in significantly reduced strain induced by the implantation, which became undetectable with presently used very sensitive synchrotron arrangement. A significant difference between the Cz-Si:H samples annealed at high and atmospheric pressure was observed. In the first case a distinct topographic contrast attributed to the formation of comparatively larger inclusions was observed. This effect was different at different temperatures. The samples annealed at enhanced pressure were more uniform and often produced significant interference effects.
18
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Composition and Structure of Czochralski Silicon Implanted with H_{2}^{+} and Annealed under Enhanced Hydrostatic Pressure

62%
Kulik M., Kobzev A., Misiuk A., Wierzchowski W., Wieteska K., Bak-Misiuk J.
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issue 2
332-335
EN
Depth distribution of implanted species and microstructure of oxygen-containing Czochralski grown silicon (Cz-Si) implanted with light ions (such as H^{+}) are strongly influenced by hydrostatic pressure applied during the post-implantation treatment. Composition and structure of Si:H prepared by implantation of Cz-Si with H_{2}^{+}; fluence D = 1.7 × 10^{17} cm^{-2}, energy E = 50 keV (projected range of H_{2}^{+}, R_{p}(H) = 275 nm), processed at up to 923 K under Ar pressure up to 1.2 GPa for up to 10 h, were investigated by elastic recoil detection Rutherford backscattering methods and the depths distributions of implanted hydrogen and also carbon, oxygen and silicon in the near surface were determined for all samples. The defect structure of Si:H was also investigated by synchrotron diffraction topography at HASYLAB (Germany). High sensitivity to strain associated with small inclusions and dislocation loops was provided by monochromatic (λ = 0.1115 nm) beam topography. High resolution X-ray diffraction was also used.
19
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Synchrotron Diffraction topography in Studying of the Defect Structure in Crystals Grown by the Czochralski Method

52%
Wierzchowski W., Wieteska K., Malinowska A., Wierzbicka E., Lefeld-Sosnowska M., Świrkowicz M., Łukasiewicz T., Pajączkowska A., Paulmann C.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
350-359
EN
The synchrotron diffraction topography had been widely used for investigation of the structural defects in crystals grown by the Czochralski method. Similarly as conventional diffraction topography, the synchrotron topography consists in recording with high spatial resolution of the beam formed by the Bragg reflection from the crystal. The advantages of synchrotron sources come from the possibilities of using the wavelength from a wide spectral range, improved high spatial resolution and collimation of the beam as well as from shortening the time necessary for the investigation. The synchrotron diffraction topography includes experimentally simpler white beam topography and more complicated monochromatic beam (multicrystal) topography, where the beam is formed by monochromators. In the case of Czochralski-grown crystals the synchrotron diffraction topography can be used for studying of the individual dislocations and their complexes such as glide bands or sub-grain boundaries, individual blocks, twinning, the domain structure and various segregation effects negatively affecting crystal properties. In addition, the topographical investigation can provide information concerning the reasons for the generation of defects, useful in the improving of the technology. In the present paper the possibilities of the synchrotron diffraction topography are discussed on the basis of several investigations of the Czochralski-grown oxide and semiconductor crystals, performed by the authors at HASYLAB. The majority of the results concern the oxide crystals grown at the Institute of Electronic Materials Technology, in particular garnets, orthovanadates, mixed calcium barium and strontium niobates as well as praseodymium lanthanum aluminates.
20
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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

52%
Wieteska K., Wierzchowski W., Malinowska A., Turczyński S., Lefeld-Sosnowska M., Pawlak D., Łukasiewicz T., Paulmann C.
Acta Physica Polonica A
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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.
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