Strukturuntersuchungen an Oberflächenschichten spanend bearbeiteter Molybdän-Einkristalle

Molybdenum single crystals were used as model samples for gross machining operations (turning). The damaged surface layer was studied by reflection electron diffraction and transmission electron microscopy (TEM). Near the machined surface the material was found to be polycrystalline, the transition to the single crystal state occurs within the range from 2 to 5 μm. Pronounced plastic deformations are ranging to a depth of about 150 μm below the surface. The transition to the undisturbed single crystal occurs within the range from 150 to 300 μm.     

Morphologische Untersuchungen an Oberflächenschichten von Stahl nach einer Drehbearbeitung

The surface morphology of machined steel C60 was investigated by comparative scanning electron micrographs and surface finish measurements. Structure changes in the boundary layer by plastic deformation could be examined using optical and electron optical observation of longitudinal cut taper sections. Both the surface roughness and the depth of changes by plastic deformation were found to increase with progressing wear of the tool. Concluding it can be stated that the additional application of scanning electron microscopy reveals more detailed informations than usual test methods alone cal deliver.     

Näherungsverfahren für die Integraldarstellung von Beugungsintensitäten gestörter Kristalle

For the calculation of the electron microscopic diffraction contrast without column approximation a solution is given by a perturbation calculation. Applying this to the two-beam case one gets integral representations for the amplitudes of the diffracted waves.     

Oberflächeneffekte an Silizium-Einkristallen

Structures of different geometry were observed on surfaces after diffusion or annealing of Si planar slices in vacuum or non-oxidizing atmosphere. Characteristic etch structures were found after arsenic diffusion under determined experimental conditions. Traces of water are considered to be the cause for the levels.     

Die Struktur der Oberfläche fester Körper

Assuming the row of particles in a lattice to extend from n = – ∞ to n = 0, with all particles n = 1, 2, 3, …︁ missing, the force is discussed to be added in order to keep the periodicity of structure near the end of the row. Forces that would make up exactly for the forces that the missing particles would produce on the end of the row must be provided for. If the total force is differently distributed between the particles at the end of the row, different things may happen, in that a perturbation appears near the end of the lattice or even along the whole lattice. This example corresponds to the problem of surface structure and surface tension for solids. The perturbation of the lattice inside a surface layer results in additional forces, the resultant of which is known as surface tension.     

Einfluß der Oberflächenbearbeitung auf die Röntgenstrahl-Totalreflexionsprofile

If X-rays are specular reflected on real surfaces it occurs a broadening of the incident X-ray beam. This broadening is a very sensitive and experimentally simple determinable value, with which it is possible to characterize the quality of light optical mirrors.     

Beziehungen zwischen Beilbyschicht und Oberfläche fester Körper

The investigation of the influence of the Beilbyschicht upon thin plates begins with the statement of the distortion of the plate by calorification during its generation. The enhancement of the temperature of the material curves the middle surface of the thin plate into a thin shell. The curvature exist after plates being cooled.     

Der Zusammenhang zwischen Oberflächenbehandlung und Barrierenhöhe bei metallkontaktiertem GaSb

Barrier heights of Ag-, Au-; Ni-, Al-; In-, Sn-contacts onto p- and n-GaSb surfaces were investigated by measuring the current-voltage characteristics. Barrier heights depend on surface conditions of semiconductor and contact metal. The results were explained by surface states, terms of trap and interfaces of chemically and mechanically polished (111) surfaces. They are due to the specific differences in the boundary conditions at the metal-semiconductor contacts and determine the quality of contacts. Sn-, Al-, Ag-contacts have „ohmic”︁ characteristics on n-GaSb, Au- and In-contacts became „ohmic”︁ contacts on chemically polished surfaces.     

Oberflächenbeurteilung von bearbeiteten Siliziumscheiben

For the judgement of various polished surfaces of silicon single disks was used the method of reflexion high energy electron diffraction (RHEED) in the electron microscope and on the other hand the X-ray-method of double crystal spectrometry. Because of the obtained diffraction pictures and the obtained rocking curves and because of the completing figures of surfaces with the replica method on the electron microscope, it is possible to estimate the silicon single disks relating to the mistakes in the surface range.     

Untersuchung epitaktischer Molybdänkarbidschichten an Molybdän-(110)-Oberflächen

The initial phases of high temperature (1700 K) carburization of (110) molybdenum surfaces by C₆H₆ at low pressure are examined with low energy electron diffraction (LEED) and emission electron microscopy. After an exposition of about 8 · 10⁻⁵ Torr · sec a (4 × 4) superstructure was observed by means of LEED, interpreted as coincidence lattices with the Mo₂C (10.0) plane parallel to the Mo (110) surface. Heating a sample without further exposition resulted in the appearance of a complex and of a (2 × 2) superstructures. After an exposition of about 2 … 9 · 10⁻³ Torr · sec needle shaped molybdenum carbide crystallites grew on the surface into the [111] and [111] directions. The orientation Mo₂C (10.1) parallel to Mo (110) was concluded from the LEED patterns.     

Anwendungsmöglichkeiten der Röntgentopographie zur Bestimmung der Oberflächengüte und der Realstruktur von Granateinkristallen

Single crystals of garnets of the rare earth are interesting in the development of bubble memories. Therefore it is necessary to controll the surface quality of the substrates and epitaxial layers during the different steps of preparation. X-ray topographic methods for testing the surfaces will be compared with the etching technique. Loop-configurations at inclusions are described and the mechanism for their formation will be discussed.     

Röntgentopographische Untersuchung von KDP-Kristallen

The dislocation configuration arising in KDP crystals grown from the solution has been studied by X-ray diffraction topography method (Lang-method). The space orientation of dislocations and their Burgersvektor directions are determinated. The dislocations density did not exceed 10³ cm⁻², and there are areas which were free form dislocations. The sources of dislocations were classified as inclusions of mother liquor and foreign particles respectively.     

Oberflächenmorphologie und Gleitverhalten trikliner Einkristalle von TCNQ-Komplexsalzen

The electron microskopic investigation of the most important crystal faces of the TCNQ-complex salts with triphenylmethylphosphonium and with triphenylmethylarsonium showed growth accessories and etch pits but also slide steps which could be provocated intentionally as by local deformations with a needle point as by axial pressure deformation. The orientation of the slide steps in different crystal faces leads to (010) as the slide plain. Axial pressure normal to the (010) faces caused unexpected strong shear deformation, which could serve for the estimation of the slide directions parallel to [101] or [101]. The sliding and cleaving parallel to (010) is favoured by the crystal structure, for (010) being parallel to a „smooth”︁ net-plain not crossed by overlapping molecules.     

LEED-Intensitätsspektren verschiedener Oberflächen des kubisch-raumzentrierten α-Eisens

LEED intensity spectra of clean Fe(100)-, Fe(110)- and Fe(111)-surfaces are calculated and compared with experimental curves of various authors. The Layer KKR method succesfully used for fcc-lattices was applied to bcc-lattices up to electron energies of 500 eV. Good conformity of theoretical and experimental spectra was established by taking into consideration a sufficient number of beams (up to 61) and a sufficient number of phase shifts (up to 8).     

Röntgenographische Untersuchung von Verformungsstrukturen in Metall-Einkristallen

Special tasks to X-ray topography for the investigation of deformation structures are discussed and different variations of the Berg-Barrett method suitable for this purpose are compared in relation to the application and the content of information. In particular orientation contrasts typical for deformation structures are dealt with on the basis of common fundamentals of image discussion and contrast interpretation. Besides the quantitative measurement of misorientations it is possible to find out the position of the axis of misorientation, the sign and the nature of lattice distortion (twist or tilt), too, if the tests are made in a convenient way.     

Oberflächenstörungen und Hohlwachstum bei der Züchtung von β-Kupferphthalocyanin-Einkristallen aus der Gasphase

Hollow crystals are obtained frequently during the growth of copper phthalocyanine single crystals from the vapour phase. This appearance makes some physical investigations impossible. To overcome these difficulties some ways are discussed. The reasons for hollow growth are instabilities in the growth caused by diffusion controlled inhomogeneities in supersaturation on the growth front. This was found by observations of surface defects and by defined growth experiments. By introduction of special methods of growth and use of defined parameters one obtains bulk crystals of larger extent up to 1 mm in cross direction. References are given in the field of hollow crystal growth in the vapour phase of other substances.     

Untersuchung der durch Metallspuren verursachten Störstellen in Si-Epitaxieschichten

In single crystal epitaxial layers of silicon and Boron-diffusion layers enrichment of special impurities as aluminium, barium, calcium, potassium, natrium, magnesium, silver, oxygen and sulphur has been found using different methods of analysis. Data of the electron microprobe analysis show that the enrichment of the mentioned contaminants leads to the formation of precipitates having different morphology and composition.