bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper precipitation in long‐time diffused silicon
Authors: Gleichmann R. , Mohr U. , Jegerlehner K. 
Published: January 2007

AbstractThe generation of microdefects in FZ‐silicon during long‐time high‐temperature processing, necessary for the production of power devices, has been investigated by etching techniques and transmission electron microscopy. The results prove the defects to be large precipitates, which may generate dislocations and stacking faults. The analysis of Moiré fringes and the interpretation of selected area diffraction patterns indicate the material to be CuSi. The experimental findings are interpreted by the help of an extension of the existing model for the copper precipitation process.
The influence of time dependence of temperature on the kinetics of nucleation
Authors: Kožíšek Z. , Chvoj Z. 
Published: January 2007

AbstractIn this work the influence of time dependence of temperature on kinetic processes during nucleation on a simple model is studied. The nucleation rate and the average effective radius of nuclei R is counted. It is proved that in the case of oscillating temperature the nucleation rate also oscillates and the rate of growth of radius R is directly proportional to frequency of temperature change.
Investigation of the structure of solid solutions of elements of the IV. group (Si, Ge) in gallium antimonide
Authors: Wilke J. , Bublik V. T. , Osvenskii V. B. , Popkov A. N. , Beaginskaya A. G. , Kolchina G. P. 
Published: January 2007

AbstractPrecision measurements of the lattice parameter and the density of Si‐ and Ge‐doped GaSb monocrystals were accomplished. The investigated crystals were Czochralski‐grown from an equiatomic melt (with respect to its own components) and doped with 2 · 1017 to 4 · 1019 cm–3 Si and 2 · 1017 to 4 · 1019 cm–3 Ge, respectively. The concentrations of the dopants were determined spectroscopically. — Hall measurements at room temperature showed that Si as well as Ge in GaSb produce p‐conduction.
Stabilization of the melt composition in GaAlSbAs
Authors: Baranov A. N. , Konnikov S. G. , Popova T. B. , Umansky V. E. , Yakovlev Yu. P. 
Published: January 2007

AbstractIn this work we present a new effect of stabilization of the GaAlSbAs melt composition when it is in contact with the GaAs substrate. It was found that the As content in the GaAlSbAs melt did not depend on the initial Sb concentration when the liquid phase was formed by saturating the GaAlSb melt from the GaAs substrate. This effect is supposed to be due to the change in phase equilibria conditions caused by large lattice mismatch between the substrate and the solid in equilibrium with the liquid.
On the origin of free carriers in high‐conducting n‐GaN
Authors: Seifert W. , Franzheld R. , Butter E. , Sobotta H. , Riede V. 
Published: January 2007

AbstractGrowth experiments with GaN in the system Ga/HCl/NH3/He at different growth temperatures show that the assumption of N‐vacancies to be responsible for the high n‐conductivity is questionable. The dependence of carrier concentration on growth temperature as well as the decrease in carrier concentration when additionally purified NH3 is used indicate that donor impurities are incorporated. The most probable impurity is oxygen, substitutionally incorporated onto N‐sites. The observed growth rate dependence of carrier concentration can well be explained by a kinetically controlled incorporation process.
A study on crystallographic characteristic of Mg‐vicariate fassaites
Authors: Krajewski A. , Foresti‐Serantoni E. 
Published: January 2007

AbstractSome relationship occurring by isomorphous change of Al3+ for Mg2+, in the presence of some impurities like iron and titanium ions, were studied.This study tooks shape as a contribution for a mineralogical and geochemical study on the contact paragenesis of Predazzo‐Monzoni's area in the northern of Italy. It reveals itself also useful to drawn‐up informations about the different influence that some network modifier cations bring into the mutual connection of chain systems, even if these cations are randomly dispersed and in a very few amount. This is useful for chemico‐physical evaluations concerning their behaviour in multicomponent silicatic compositions whether in lattice systems as crystals or in random systems as glasses and glazes, very important in the sector of glasses and ceramics where direct informations on cations influence are more and more difficult to make display.Some results are according to some observations displayed in previous studies on amphiboles (Rossi, Ungaretti), where a certain influence of Ti4+ and Fe3+ on some parameters were observed.
Crystallization of potassium sulfate from pure aqueous solution and in presence of surfactants
Authors: Kuschel F. , König An. , Herold S. 
Published: January 2007

AbstractThe use of surfactants offers an interesting possibility to control the crystallization from solutions. There are already some applications in technical scale. Yet, little knowledge exists on the mechanism of the effect and his dependence on surfactant concentration. Therefore, the displacement rates of selected single crystal faces of K2SO4 in pure aqueous solutions and in presence of different amounts of tensides have been measured. Furthermore, in order to get insight into the state of surfactant solutions existing in the interesting concentration interval, the critical micelle concentrations have been determined. In comparison with growth from pure solution, the admixtures caused at concentrations below 10−5 mol/l no drastic alterations. On the contrary, above a transition region characterized by a very irregular growth, a practically totally inhibition of growth as well as of dissolution was observed. The changes of surface morphology induced by surfactants have been investigated using the phase contrast microscopy.
Estimation of the debye temperature of diamond‐like semiconducting compounds from bulk modul and microhardness
Authors: Deus P. , Schneider H. A. 
Published: January 2007

AbstractThe reliability of estimation of Debye temperature θD evaluated from bulk modul and microhardness is proved for semiconductors with diamond, sphalerite, and chalcopyrite structure. The known linear relations available from the literature do not yield a reasonable agreement between experimental and calculated Debye temperatures. As in the case of the Lindemann rule a better approximation is obtained by use of a more general relation θD = a1x + a2. The constants a1 and a2 are calculated for the substances under consideration. Unknown Debye temperatures are calculated.
Growth of InAs1–ySby solid solutions for obtaining decreased lattice mismatch in the InAs‐GaSb (AlxGa1–nSb) system
Authors: Pramatarova L. D. 
Published: January 2007

AbstractThis paper presents the results of investigation of the technological conditions of LPE growth of InAs1–ySby solid solutions on InAs substrates. It is shown that the chosen regions of composition of InAs1–ySby solid solutions and experimentally determined technological conditions allow the obtaining of InAs1–ySby solid solutions with lattice parameter values close to those of the AlxGa1–xSb (0 ≦ x ≦ 0.2) solid solutions.
Expressions for driving force in crystallisation with special reference to precipitation of barium cromate from homogeneous solution
Authors: de Silva R. L. , Barker P. E. , Creasy D. E. 
Published: January 2007

AbstractDifferent expressions used to represent driving force for crystal growth, on the basis of fundamental thermodynamic considerations as well as on empirical grounds, are briefly reviewed. The choice of driving force expression for the crystal growth of barium chromate, when precipitation was carried out from homogeneous solution, is described and the reasons for the final choice are discussed.
On the structure of the rhombohedral α′R‐phase in Al Zn alloys
Authors: Werner M. , Ramlau R. , Löffler H. 
Published: January 2007

AbstractThe lattice parameters α and α of precipitates of the rhombohedral α′R‐phase grown in two AlZn alloys with 10 and 12 at.% Zn, respectively, at elevated temperatures were determined by transmission electron microscopy (TEM). Two approximative methods were derived to evaluate the Moiré fringes occuring in the TEM micrographs. The results obtained by these two methods agree within the range of experimental error with those presented in the literature (mainly gained from X‐ray methods).
Vibrational entropy of substitutional solid solutions
Authors: Urosov V. S. , Kravchuk I. F. 
Published: January 2007

AbstractPositive deviations of the entropy of mixing from that of the ideal case have been established basing upon the experimental study of ionic substitutional solid solutions, carried out with the help of various techniques. These deviations are attached to the vibrational entropy, corresponding to the negative deviations of Debye temperatures of solid solution from additivity. The existence of linear correlation between the enthalpy of mixing and vibrational contribution to entropy is confirmed. Theoretical basis of this correlation, established empirically for the alkali halogenides, is given. The question is discussed, dealing with the universality of the relations of that kind and independence of vibrational entropy on temperature.
Electron microscopic investigations of precipitates in doped NaCl crystals
Authors: Raju I. V. K. Bhagavan 
Published: January 2007

AbstractPrecipitation morphology of NaCl:CdCl2 and NaCl:SrCl2 crystals is investigated by high voltage transmission electron microscopy. The volume fraction of the precipitates and the content of CdCl2 has been evaluated using the theory developed by Hillard. Selected area diffraction patterns of the precipitates and investigations of the misfit dislocations around the precipitates is presented.
Dislocation activity in single crystals of stannic iodide
Authors: Desai C. C. , Rai J. L. 
Published: January 2007

AbstractSingle crystals of stannic iodide (SnI4) have been grown employing the controlled‐reaction between SnCl2 and KI solutions by diffusion process in silica gels. As‐grown (111) surfaces of the crystals have been optically studied. Characteristic growth spirals and hopper growth patterns have been observed on them. By successively etching (111) surfaces in a 0.2 N HCl solution, it is established that the pits indicate the sites of dislocations in the crystals. This is further confirmed by comparing the etch patterns before and after chemically polishing (111) surfaces. The average dislocation in the SnI4 crystals have been determined and found to be 7.3 × 102 cm−2. Observations of polygonisations are described and the implications are discussed.
Investigation of the nature of point defects in in Te‐doped gallium antimonide
Authors: Wilke J. , Bublik V. T. , Osvenskii V. B. , Popkov A. N. , Braginskaya A. G. , Kolchina P. P. 
Published: January 2007

AbstractPrecision lattice constant and density measurements held on gallium antimonide single crystals grown from stoichiometric melts showed that doping of such crystals with Te lead to the intensification of Ga‐supersaturated solid solution decomposition process with initial Frenkel defect (Gai + VGa) production. It is supposed that Tesb — simple donors form complexes with VGa which are believed to be acceptors. Doping of GaSb with Te up to the levels above 2 · 1018 cm−3 leads to partial decomposition of GaSb(Te) solid solution supersaturated with Te.
Vacancy formation enthalpies in AIBIIIC chalcopyrite semiconductors
Authors: Neumann H. 
Published: January 2007

AbstractFormation enthalpies ΔHv of single vacancies in all AIBIIIC2VI chalcopyrite structure compounds are estimated using the macroscopic cavity model. A comparison with atomic sublimation enthalpies ΔHsub of the BIII and CVI atoms derived from existing partial vapour pressure data shows that within the accuracy of this data and the theoretical calculations the relation ΔHv ⪆ ΔHsub is fulfilled as expected from general considerations.
Cathodoluminescent efficiency of Y3Al5O12 and YAlO3 single crystals in dependence on Ce3+ and other dopants concentration
Authors: Autrata R. , Schauer P. , Kvapil Jo. , Kvapil Ji. 
Published: January 2007

AbstractThe content of Ce3+ ions in the investigated single crystals grown under reducing conditions is limited by a low value of the distribution coefficient. This distribution coefficient decreases sharply with increasing concentration of Ce3+ ions in a melt. Cathodoluminescent efficiency rises with increasing Ce3+ concentration up to a certain state of saturation. At higher concentrations of Ce3+ ions emission from activator centres is dominant, while at lower concentrations defect centres play an important part. Iron acts as a strong quenching centre, especially in the YAlO3 lattice. Nd, Ir, Fe, Ti, Cr centres exhibit a high quenching effect, too. A trace amount of Mo enhances cathodoluminescent efficiency.
Chiral SmC* liquid crystals obtained by mixing of SmC and cholesteric phase
Authors: Pavel J. , Glogarová M. , Demus D. , Mädicke A. , Pelzl G. 
Published: January 2007

AbstractThe binary mixtures of the substance magnified image providing cholesteric phase exhibit a chiral SmC* phase for certain concentration and temperature range. This phase was verified to be ferroelectric. The temperature dependences of the spontaneous polarization and the coercive field were determined for three concentrations. The pitch of the helical structure is approximately indirectly proportional to the molar concentration of the cholesteric substance and varies from 3 μm to about 25 μm in the concentration range from 20 mol% to 5 mol% of the cholesteric substance. For the lower concentrations the sample is unwound in planar samples due to the surface anchoring. Two possible unwound planar configurations can be switched by electric field.
Copper precipitation in long‐time processed transistor samples
Authors: Gleichmann R. , Breitenstein O. , Mohr U. 
Published: January 2007

AbstractProcess‐induced crystal defects (point defects and extended defects) in completely processed transistor samples of floating zone silicon have been investigated by TEM analysis and DLTS measurements. It was possible to demonstrate that the lifetime of these samples is determined by the introduction of copper during the long‐time processing of the wafers. The predominant crystal defects within the wafer volume were found to be circular monolayers of copper silicide which due to their appearance could be easily confounded with stacking faults.
X‐ray and scanning cathodoluminescence imaging of small‐angle grain boundaries and dislocations in CdTe crystals
Authors: Klimkiewicz M. , Auleytner J. 
Published: January 2007

AbstractBy employing the Reflection X‐ray Topography (RXT), on one hand, and the Cathodoluminescence (CL‐IR) mode of operation of the Scanning Electron Microscope, on the other hand, wer are able to visualize the lattice defects in CdTe single crystals. The possibility of defect identification is the advantage of the RXT technique. Moreover, the examined surface can be imaged as a whole. Cathodoluminescence, however, guarantees higher resolution. The defects in CdTe crystals, observed in cathodoluminescence images, have been identified as small‐angle boundaries and screw dislocations.
Dependence of refractive indexes dispersion for LiNbO3 on impurity
Authors: Bodnar I. T. , Yarunichev V. P. 
Published: January 2007

AbstractThe effect of the impurities of the transition metals Co, Mn, Cr, Fe, Ni, Cu on the dispersion of the refractive indexes of LiNbO3 is studied. The dispersion curves for LiNbO3 are compared to those for the pure crystals. The relation between the difference of the refractive indexes of the pure and doped LiNbO3 and the ionic radius of the impurity is established.
Electrical properties of ZnO single crystals annealed in a zinc atmosphere
Authors: Ziegler E. , Heinrich A. , Oppermann H. , Stöver G. 
Published: January 2007

AbstractThe electrical conductivity and the Hall coefficient of ZnO single crystals annealed in a zinc atmosphere after growth were measured in a temperature range from 77 K to 1000 K. The results are compared with those of ZnO crystals from the zinc rich phase boundary. A shallow level with an activation energy at about 15 meV dominates in both groups of samples. Its concentration was found to correlate directly with the degree of non‐stoichiometry.
Structure refinement of an 1M‐lepidolite
Authors: Backhaus K. O. 
Published: January 2007

AbstractThe structure of an 1M‐lepidolite from Wakefield (Canada) has been investigated by X‐ray diffraction structure analysis. The refined atomic coordinates and occupation factors indicate an ordered distribution of the octahedrally coordinated cations. The structure has the space group C 2. The tetrahedra do not show any remarkable ordering of their central cations. Octahedral flattening is characterized by a mean octahedral angle of 58.66°. The tetrahedral rotation angle is equal to 5.9°.
EPR studies on Mn2+ centres in solid solutions of TSCC and TSCB
Authors: Küchler J. , Malige B. , Meister R. , Triebeneck R. , Windsch W. 
Published: January 2007

AbstractEPR investigations of Mn2+‐doped solid solutions of TSCC and TSCB were performed between 130 K and 300 K. The axial fine structure parameter D vs bromine concentration x is nonlinear. The relation between the axial fine structure parameter and bromine concentration is discussed by means of a simple statistical model.
Application of the iodide synthesis to the preparation of indium arsenide bulk crystals and epitaxial layers
Authors: Trifonova E. F. , Karagiozov L. , Hitova L. 
Published: January 2007

AbstractBulk crystals and epitaxial layers have been prepared from iodidely synthesized InAs. Their parameters have been studied and compared with those of high‐temperature synthesized InAs. The synthesis mixture composition substantially effects the electrical parameters of the samples. Iodine is supposed to be a donor‐acting impurity in iodidely synthesized InAs.
Mechanism of chemical dissolution of calcite in lactic acid
Authors: Bhagia L. J. , Pandya J. R. 
Published: January 2007

AbstractEffect of etching time and temperature on morphology of etch pits and etch rates in controlled dissolution of calcite by lactic acid it optically investigated in detail. Arrhenius equation is used to determine activation energy which is observed to change with the morphology of etch pits. Further, an attempt is made to understand the mechanism of dissolution by considering Laidler's theory of heterogeneous catalytic reactions.
A study of Z1‐centers in γ‐irradiated KCl:Ba2+ crystals
Authors: Reddy K. Narasimha , Rao U. V. Subba , Babu Hari 
Published: January 2007

AbstractThe purpose of the paper is to report the optical absorption and thermoluminescence measurements on KCl: Ba2+ crystal irradiated with γ‐rays. Bleaching in F‐band increases the glow peak around 75 °C and suppresses the 125 °C peak. A similar result is observed in preheat treated crystals. When this peak is thermally cleaned, the broadening of the absorption on the prolonged F‐bleached crystals is removed. On the basis of these observations, the glow peak at 75 °C is tentatively attributed to Z1‐centers.
I–V characteristics and break down studies of Sb2O3 structures
Authors: Kumar J. Siva , Narayana G. , Shekar M. Chandra , Rao U. V. Subba , Babu V. Hari 
Published: January 2007

AbstractI–V characteristics of sandwiched Al–Sb2O3–Al structures have been studied for different thicknesses. The current‐voltage curves in general exhibit three regions, ohmic, non ohmic and breakdown regions. The breakdown voltage increases whereas the dielectric strength decreases with increase in Sb2O3 film thickness. The electrical breakdown studies have been done for dc and ac voltages and optical photomicrographs of breakdown patterns during different stages of voltage have been taken and the results are explained.
Electrical characteristics of GaAs LPE schottky diodes
Authors: Konakova R. V. , Tkhorik Yu. A. , Zaitsevskii I. L. , Benč V. , Morvic M. , Kordoš P. , Červenák J. 
Published: January 2007

AbstractStructural and electrical properties of IMPATT diodes prepared from homoepitaxial GaAs films grown by liquid phase epitaxy have been investigated with the help of metallography and reverse I–V characteristic derivatives. The structural defects in epitaxial layers have been shown lead to the localization of current in separate regions (microplasmas) which brings up a soft breakdown. A method as been proposed for the observation of microplasmas at large currents.
Growth and structural characteristics of the chalcopyrite semiconductor CuInSe2
Authors: Janam Ram , Srivastava O. N. 
Published: January 2007

AbstractThe growth and structural characteristics of chalcopyrite semiconductor CuInSe2 have been investigated with particular emphasis on the photovoltaic behaviour of the CdS/CuInSe2 thin film heterojunction. It has been found that the structural phase of the CuInSe2 has an important bearing on the photovoltaic behaviour of the heterojunction. Thus the heterojunctions having the sphalerite type cubic CuInSe2 as one of its component have been found to possess better conversion effciency than those employing the chalcopyrite type tetragonal form of CuInSe2. Evidences and argument have been put forward to show that the better efficiency with sphalerite phase arises due to smaller lattice mismatch with CdS base. In addition to the type of structural phase, the state of order of CuInSe2 phase has been found to affect the performance of heterojunctions. The heterojunctions having the disordered sphalerite type CuInSe2 structure exhibits a much lower efficiency than those embodying the ordered CuInSe2 phase.
Doping process control in silicon epitaxy (I). System identification
Authors: Kósza G. , Morgenstern T. , Richter F. , Valkó P. 
Published: January 2007

AbstractThe transition behaviour of the phosphorus incorporation in silicon epitaxial layers grown in a CVD reactor has been investigated, considering the reactor as a linear control system with u = lg p0PH3 (t) as the input and y = lg N(t) as the output. The response of system to both upward and downward step inputs has been studied experimentally, using SiH4 and PH3 sources. The dopant system of a horizontal silicon epitaxial reactor has been identified and a mathematical model relating to the transient behaviour of the system has been found. The parameters of the model have been estimated from layer growth experiments. The step response functions found can be approximated by an exponential function relating to n time constants T, all equal to each other. It was found for the system investigated that the second order model is of sufficient accuracy for the optimal control calculations described in the next part of this series.
X‐ray double crystal diffractometer for testing of plane analyser crystals of LiF
Authors: Dressler L. , Wehrhan O. 
Published: January 2007

AbstractA double crystal diffractometer (DCD) for testing LiF crystals is presented. It is possible to distinguish in a relatively short measuring time (nearly 10 minutes including change of sample and adjustment) between crystals with block desorientation angles >1′ and ≦ 1′ (1′ = 0.291 · 10−3 rad). The extention of area registered during a measurement depends on the kind of section of crystal and the kind of reflection; at the examination of {100}‐cleavage faces of LiF an elliptical area of a height of 15 mm and a length of 115 mm is registered.
Lattice disorder and optical absorption of PbTiO3 crystals
Authors: Bollmann W. , Wehrhan G. 
Published: January 2007

AbstractThe electric conductivity and the optical absorption of PbTiO3 crystals are explained by the existence of Pb3+ ions and free holes as electronic defects and of O– vacancies and interstitials as ionic anti‐Frenkel defects. The absorption band at 475 nm is caused by Pb3+ ions and produces the yellowish or brownish colour of the crystals. Using fluoridic fluxes instead of oxidic fluxes for the crystals growth a small part of O– ions is replaced by F− foreign ions. This substitution diminishes the Pb3+ ion content and causes an increased optical transmission of the PbTiO3 crystals.