共查询到20条相似文献,搜索用时 31 毫秒
1.
E. Butter R. Günther B. Jacobs K. Jacobs P. Streubel A. Zehe 《Crystal Research and Technology》1973,8(9):1021-1028
This communication reports on etching of {110} cleaved faces of (Ga,Al)As/GaAs heterostructures with and without an additional pn-junction. The etching agents are dilute HNO3 and mixtures of NH3 and H2O2. The lines appearing in the etch patterns are attributed to the related steep changes in the physicochemical features of the crystals. The etch patterns can be correlated with the aluminum concentration profiles throughout the epitaxial layers as obtained by electron microprobe analysis. The optimum temperatures, times and compositions of the etch solutions are given. Preferential etching of GaAs by NH3/H2O2 mixtures is discussed. 相似文献
2.
M. Schreckenbach 《Crystal Research and Technology》1971,6(6):757-767
In silicon crystals a real etching structure can be visualized by means of a suitable method of etching also in the domains free from dislocations. The shapes of etch pits are chiefly dependent on the orientation of the grinding faces. It may be that the etching structure comes from growth domains, bordered by faces {111}, at which impurities are segregated or adsorbed. 相似文献
3.
I. Hhnert 《Crystal Research and Technology》1972,7(4):419-426
This paper presents investigations on etching of KAl-, NH4Al-, KCr- and K(Al, Cr)-alum crystals. The etchant was a solution of tartaric acid in ethyl alcohol which produces well-defined etch pits on {111} faces. The correspondence of etch pits with dislocations was investigated by KAl-alum crystals. Between microscopic holes in the crystals and dislocations are not stated. 相似文献
4.
B. Brenner 《Crystal Research and Technology》1978,13(8):957-968
The temperature dependence of microhardness on {100}-surfaces of iron single crystals was determined in the temperature range between 200 K and 1180 K. The dislocation structure around the microindentations is investigated by transmission electron microscopy, optical microscopy and etching. The results suggest that the separate ranges of the microhardness-temperature-dependence coincide with characteristic dislocation arrangements. Possible deformation processes are discussed. 相似文献
5.
6.
A quantitative estimation of the structure of etched silicon crystals is possible with the microscope Quantimet by a fast counting the number of particles, i.e. etch pits on {111}-planes. Boundary conditions of the measuring technique are the requisite size of the etch pits of from > 3 … 5 μm, a plane specimen surface, the correct optical magnification, threshold and acceptance width. Sources of errors due to the structure result from the overlap of etch pits at dislocation densities > 104 cm−2 which leads to an underestimation of the number of etch pits because of the reduced signal output. An overestimation is most caused by an unwished contrast in the surface which yields additional signal outputs. The errors will be eliminated by using a calibration curved. Due to the short time which is necessary for counting, the Quantimet is well suitable for routine testings and for quantitative evaluation of the structure defects (etch pit density) in silicon, including consideration of possible errors. 相似文献
7.
The quality of (100), (110), and (111) oriented spinel substrates in the composition range MgO × 3.3-3.5 Al2O3 is examined by chemical etching. The investigation shows that KHSO4, H3PO4, and Na2B4O7 cause dislocation etch pits on (111), and only KHSO4 on (100) faces. The little rod-shaped defects revealed by etching on (100), (110), and (111) faces were found to be Al2O3 precipitates. 相似文献
8.
An etching technique was developed to investigate dislocations in β-copper phthalocyanine single crystals. Considering the expected content of dislocations and the etch pit symmetry the symmetric etch pits are correlated to [010]-edge dislocations on {201 }- and {001}-lattice planes with (001)- and (201 )-slip planes. Asymmetric etch pits on {001}- and {201 }-planes are connected with [010]-edge dislocations related to (100)- and (101 )-slip planes. The dislocation density on growth planes and cleavage planes is commonly lower than 100 cm−2. [010]-screw dislocations are not observed, but their existence could not be excluded. 相似文献
9.
AgGaSe2 thin epitaxial layers onto {100} and {110} oriented GaAs substrates were prepared by flash evaporation technique and investigated by the RHEED method (reflection high energy electron diffraction). Special epitaxial relationships were found and the results will be discussed. 相似文献
10.
Nadia Belfguira Siwar Walha Abdelhamid Ben Salah Frédéric Hatert André Mathieu Fransolet Ahlem Kabadou 《Journal of chemical crystallography》2010,40(12):1125-1128
Abstract
Single crystals of iron and manganese phosphate Fe6.36Mn0.64(PO3(OH))4(PO4)2 was synthesized by hydrothermal method. The compound crystallizes in the Fe7(PO4)6 structure type and is isotypic with the solid solution \textM7 - \textx \textM\textx¢ ( \textHPO4 )4 ( \textPO4 )2 {\text{M}}_{{7 - {\text{x}}}} {\text{M}}_{\text{x}}^{\prime} \left( {{\text{HPO}}_{4} } \right)_{4} \left( {{\text{PO}}_{4} } \right)_{2} where M is Fe, Co, Mg, Mn. The compound is triclinic, P-1, a = 6.571(5), b = 7.993(3), c = 9.547(2) Ǻ, α = 103.97(1)°, β = 109.29(2)°, γ = 101.57(3)°. The structure is based on a three-dimensional framework of distorted edge-sharing MO6 and MO5 polyhedra, forming infinite chains, which are interlinked by corner-sharing with PO4 tetrahedra. The formula unit is centrosymmetric, with all atoms in general positions except for one Fe atom, which has site symmetry −1. 相似文献11.
Epitaxial LiInSe2 films were deposited by flash evaporation technique on {100}, {110} GaAs and {100} GaP. By means of geometrical considerations based on the concept of corresponding substrate and deposit planes epitaxial relationships can be predicted and compared with results from reflection high energy electron diffraction (RHEED). The epitaxial relationships are given for both rhombic (β-NaFeO2-type) and tetragonal (chalcopyrite-type) LiInSe2 deposits on {100}- and {110}-oriented sphalerite-type substrates. 相似文献
12.
From the measurement of X-ray intensity differences of opposite {111}-surfaces in Ga1 – xAlxAs- und Ga1 – xAlxSb-mixed crystals with high Al concentration it was concluded which of the two surfaces is terminated by a layer of the group V atoms. The results are correlated with etching studies. 相似文献
13.
W. Bollmann 《Crystal Research and Technology》1980,15(5):585-594
From differential thermal analysis (DTA), thermal etching, perfectly reversable redox treatments and electric conductivity it is concluded that the Pb/Mo ratio of the PbMoO4 crystals is always 1 and that phase transitions do not occur. Pb3+ ions detectable by an absorption band at 435 nm cause a p-conductivity due to the reaction Pb3+ ⇌ Pb++ + e+. At elevated temperatures the p-conductivity increases with increasing oxygen partial pressure of the surrounding atmosphere. The influence of foreign ions on the concentration of ionic and electronic defects in PbMoO4, CaMoO4, PbO, and PbTiO3 can be explained by an anti-Frenkel disorder of the oxygen ion sublattice. For PbMoO4 crystals the mobility O− ion vacancies and the free formation enthalpy of anti-Frenkel defects are found to be vv = \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop - \limits_T^{9160} $\end{document} exp (−1.15 eV/kT) cm2 K/Vs and gAF = 3.6kT −2.2 eV, respectively. 相似文献
14.
E. Butter B. Jacobs H. Krmer W. Schmidt J. Stary W. Wolff 《Crystal Research and Technology》1975,10(5):553-560
Ga1–xInxAs epitaxial layers (0.02 ≦ × ≦ 0.12) are grown on (111)-oriented GaAs substrates from nonstoichiometric melts. The etch pit densities – determined by chemical etching – yield values between 2 · 105 cm−2 and 3 · 107 cm−2 and were found to be dependent on composition, layer thickness and cooling rate. X-ray topography of cleaved {110}-planes gives information on layer quality and indicates the existence of stress in the substrate lattice near the heterojunction. The validity of Vegard's law in the investigated concentration range was confirmed by X-ray determination of the lattice constants. The half width of double crystal spectrometer rocking-curves, the epd and the relative intensity of photoluminescence show similar dependence on the composition of the mixed crystal layers. 相似文献
15.
The change of the dislocation arrangements around microindentations after indentation test has been investigated by TEM and etching. The indentations were generated on {100} - surfaces of iron single crystals at temperatures between 800 K and 1000 K. The change of the dislocation structure was found to depend strongly on stress and dislocation density in the deformation field. The deformation field especially acts as a dislocation source operating over long periods. The results suggest that the propagation of emitted dislocations is controlled by dragging of Cottrell-atmospheres of carbon atoms. Conclusions regarding the hardness-temperature relation in pure iron are drawn. 相似文献
16.
Semiconductors of the AIBIIIC2VI type, crystallizing in the chalcopyrite structure, grow epitaxially with their {112}-planes on monocrystalline substrates with a three-fold symmetry of faces. It is shown that application of the RHEED technique permits definitively to decide what kind of epitaxial overgrowth takes place, supposing the atomic scattering factors of the I and III atoms are sufficiently different and/or the c/a axis ratio differs markedly from 2. CuInSe2/GaAs and CuGaSe2/GaAs show one-dimensional epitaxy 相似文献
17.
Abdullah Aydın Mehmet Akkurt Leyla Uzun Leyla Yıldırım Tijen Önkol 《Journal of chemical crystallography》2010,40(10):816-820
Abstract
The title compound {6-[2-(2-chlorophenyl)-1,3-thiazol-4-yl]-2-oxo-1,3-benzothiazol-3(2H)-yl}acetic acid was prepared and characterized by elemental analyses, FT-IR, 1H NMR spectroscopy, X-ray diffraction. A quantum-chemical calculation was performed using the CNDO method. In the title compound, C18H11ClN2O3S2, the crystal structure is stabilized by intermolecular hydrogen bonds (C–H···O=C) to form centrosymmetric R22 R_{2}^{2} (16) dimers and the C–H···O, O–H···N, and C–H···N interactions generating the graph set motifs R22 R_{2}^{2} (9) and R22 R_{2}^{2} (22). 相似文献18.
M. Diallo M. Diop P. M. Haba M. Gaye A. S. Sall A. H. Barry C. Beghidja R. Welter 《Journal of chemical crystallography》2008,38(6):475-478
Abstract Single crystals of new open-framework lanthanide sulphate nitrite La(NO2)(SO4)(H2O) has been synthesized, in the presence of 2,6-diformyl-4-chlorophenol. His structure has been determined by X-ray diffraction
data: the complex crystallizes in the tetragonal system, space group P43, with a = 7.0028(2) (?), b = 7.0028(2) (?), c = 11.8341(4) ?, V = 580.34(3) ?3, Z = 4, D
c = 3.582 Mg m−3. The three-dimensional (3D) framework of this compound is built up by the linkages of lanthanide atoms and the oxygen atoms
of the sulphate
and nitrite groups. The lanthanum atom is 9-fold coordinated. The structure is unfamiliar in lanthanide chemistry and this compound represents
the first example of nitrite lanthanide sulphate complex.
Graphical Abstract An unfamiliar structure in lanthanide chemistry represented by the first example of nitrite lanthanide sulphate complex is
described.
相似文献
19.
The twinning morphology of β-BaB2O4 crystal grown by TSSG has been studied on the basis of crystallography. It was found that the faces R{101-2} and r{011-4} are often intergrown together by either r{011-4} intergrown in R{101-2} or in reverse, two individuals mostly take X(112-0) and occasionally take Y(011-0) as twin boundary; and that two individuals in the twin could take the same or opposite crystallographic polarity, this was identified by surface etched figures and the piezoelectric measurements. The formation of the twinned crystals are discussed from the crystallographic structural characteristics and the energetic considerations. The experimental factors such as crystal seed quality are suggested to reduce or eliminate the twin formation and to improve the crystal quality. 相似文献
20.
The thermodynamic relationship between the transition metal dioxides and their tetrahalogenides is demonstrated, and a comprehensive survey on the thermodynamic values of the compounds is given. – All dioxides of the transition metals existing to 1000°C in the solid state are transportable by TeCl4. Only those dioxides are transported by TeBr4 which have corresponding oxide-bromides existing in the gaseous phase. – The forms of crystallographic growth are very similar. The favoured growth direction is [001], the crystal faces are {110}- and {100}-prisms, {101}- and {111}-pyramids, respectively. 相似文献