Zur Existenz von mikroskopisch kleinen Hohlräumen in durch Massenkristallisation gewonnenen KCl- und NaCl- Kristallen

By scanning microscopic investigation cavities starting from the centre of the cube faces were found in KCl and NaCl crystals which was confirmed by consequent light microskopic observations. The KCl crystals were obtained as well from a saturated solution stirred well all the time as by cooling and precipitating crystallization, while the NaCl crystals were produced by precipitating crystallization using organic solvents.     

Physikalische Eigenschaften von nach einer modifizierten Kyropoulos-Methode gezüchteten NaCl- und KCl-Kristallen

The physical properties of NaCl and KCl crystals prepared from melts by the Kyropoulos method are described. The material was firstly refined by phosgen (COCl₂) by which the anion impurities were removed from the melt. The measurements of the absorption in UV and IR region, the microhardness and CRSS, the dislocation densities, the ionic conductivity and the study of the kinetics of colour centres show that crystals prepared by the described modified Kyropoulos method are not only free from OH⁻ ions but also from all other foreign anions with oxygen.     

Eigenschaften und Kristallzüchtung von Oxiden mit Halbleiter-Metall-Übergängen

This review reports the possibilities of crystal growth for oxides of vanadium and titanium having semoconductor-to-metal transitions. The favoured methods of crystal growth, chemical transport reactions, and the flux melts are discussed in detail.     

Zur Abschätzung physikalischer und physikalisch-chemischer Daten von AlBV-Verbindungen mit Zinkblendestruktur

The AlB^V-compounds display an exceptional position among A^IIIB^V-compounds regarding some properties which are related to the lattice constant. This behaviour is connected with the absence of core-d-electrons in Al. The compressibilities of AlP, AlAs and AlSb can be estimated from the lattice constant and the microhardness in fair agreement with calculated values. Relations between the lattice constants, molecular weight, some band structure parameters, the heats of formation and the surface energies are discussed. Phillips' ionicity parameter of AlSb is corrected and the bowing parameter of the energy gap of mixed AlB^V-compounds is calculated from the difference of the atomic radii of the substitutes.     

Die Änderung der Molekül- und Kristallstruktur des N-Methyl-piperidinum-acet-meta-chlor-anilid-jodid durch Einlagerung von Wasser

N-Methyl-piperidinium-acet-meta-chloro-anilide-iodide crystallizes from water in the space group Pna2₁ with 4 formula units C₁₄H₂₀N₂OClJ and 4 H₂O molecules in the unit cell. The lattice constants are a = 12.413 Å, b = 19.798 Å and c = 6.919 Å. The change of the molecular conformation caused by water molecules was investigated by X-ray structure analysis.     

Untersuchungen zur Konzentration und Ausheilkinetik von Kristallbaufehlern in Metallen mit Hilfe der Positronenannihilation. Kurzer Abriß und Literaturübersicht

The basis and the use of the positron annihilation method for the study of crystal lattice defects in metals is shortly described. It follows a structured review on publications of last years.     

Die Herstellung von einkristallinen Dünnschichten aus Halbleitern mit ausgeprägter Anisotropie durch gerichtete Kristallisation der Schmelze zwischen zwei Substraten

Investigation of monocrystalline thin layers (5 to 150 μm in thickness) of Te and CdSb orientedly grown between two substrates. The form of the solidifying front strongly influencing crystal perfection can be controlled. Thin layers grown with velocities < 0.25 cm · min⁻¹ are monocrystalline with etch pit densities of 6 · 10² cm⁻². The electrical quantities R_H, σ and α of the layers are nearly identical with those of bulk material. Doped monocrystalline CdSb layers had a minority carrier concentration of ∼ 10¹⁴ cm⁻³ at 77°K.     

Beiträge zum Ätzen von Galliumarsenid (I) Strukturtheoretische Diskussion der erzeugten Ätzmorphologien

{111}-, {110}- and {100}-plates of GaAs have been etched in various etching solutions followed by comparing the obtained etching structures. The fundamentals of the discussion is the existing correlation between the morphology of etch pits and crystal structure. It is shown that a qualitative interpretation of the manifold etching phenomena on the above faces in a structure characteristic for GaAs can be given by including 1. the presence of primary defects as a constitutive property of real crystals and 2. the consideration of recordable influences of the surroundings.     

Zum Wachstum von AIIIBV-Halbleitern aus nichtstöchiometrischen Schmelzen (II) Dotierung von GaAs und Ga1−xAlxAs mit Zink

Doping of GaAs and Ga_1−xAl_xAs with Zn in the LPE process was studied by a radioanalytical method. It is found that Zn diffuses from the Ga-(Al)-As-Zn-solution into the n-GaAs substrate before epitaxial growth starts. This “pre-diffusion” and the following diffusion of Zn out of the epitaxial layer into the substrate results in three regions with distinct Zn-graduation in the vicinity of the pn-junction. There are no striking differences for GaAs/GaAs and Ga_1−xAl_xAs/GaAs structures. The Zn concentration in GaAs epitaxial layers decreases exponentially from the substrate up to the layer surface. From this profile the temperature dependence of the Zn segregation coefficient is calculated. At 900°C a value k_eff = 5,2 · 10⁻² is found. The doping profile in Ga_1−xAl/As layers is more complex. It is influenced by the changings of temperature during the growth of the layer and by the nonuniform Aldistribution over the layer thickness.     

Darstellung von VO2-einkristallen der oberen und unteren phasengrenze durch chemischen transport

The chemical transport of VO₂ with TeCl₄ was investigated in the temperature range of about 1000°C and 600°C. In the first case there is TeO₂ existing in the gaseous phase, in the second case the TeO₂ has no noticeable vapour pressure. The transport takes place from the hot to the cool zone. In both cases we obtained high transport rates of 10 to 20 mg h^-1. The composition of the gaseous phase is calculated and the transport mechanisms are discussed. It is possible to obtain VO₂ with the upper and lower phase boundary by variation of the initial compositions. Starting with compositions lower than VO_1.99 we obtained near 1000°C in the deposition zone V₈O₁₅ first and after a time VO₂ with the lower phase boundary. Compositions higher than VO_2.00 give vanadium dioxide with the upper phase boundary. In the temperature range of about 600°C however we obtained the phase with the higher oxygen content first. The results are compared with those, which have been obtained by the transport of VO₂ with HCl and Cl₂ — which takes place from the cool to the hot zone.     

Züchtung und optisches Verhalten von BiOCl-Kristallen

Conditions for crystal growth of BiOCl crystals from the vapour phase were found and the absorption and Raman spectren determined.     

Die Lösung von Halbleiterproblemen mit der Elektronenstrahlmikrosonde

The use of electron beam X-ray microprobe testing in the chemical analysis of semiconductor materials and devices and also in the measurement of the p n junction electrical parameters is reported. Results of analyses are presented on the precipitation of impurities and on various effects of the contaminants on device parameters. It is shown that the display of p n junction structure and also the detection of failure types is possible by using the induced current mode method.     

Untersuchungen zur Wechselwirkung von Ar-, O2- und H2-Niederdruckplasmen mit Metallschichten

By the interaction of the positiv column of a glow discharge (plasma gases: Ar, O₂, H₂) with the surface of metal films (Au, Ni, Sn) sputtering processes are observed. The sputter yields are larger than will be assumed from known yields of low energetic ions which are dominant in the investigated surface layer. Impulse interaction increases the sputter yields. This effect is reduced to a destruction of metal lattice caused by reconstruction of the surface layer and the inertion of gases during the intervals between the impulses. The sputter yields strongly depend on the plasma gases and the current density directed to the wall (i_W ∼10⁻⁵ A. cm⁻²) it is possible by decreasing the sputter yield to observer reactive processes and gas insertion in consequence of the plasma-wall interaction. Sustained upon electron diffraction of Ni- and Au-films and kinetic analysis of sputter yields a model is developed assuming a critical surface layer of 30–50 Å thickness during the plasma influence in “equilibrium” with a metal vapour-plasma gas phase above it.     

Die Präparation von GaAs-Substraten,untersucht mit Reflexionselektroneninterferenzen

The RHEED-method is used for the examination and characterization of gallium arsenide substrates. It is shown the use of both beam focussing at the object and at the photoplate in studying this subject. It was found that the samples after abrasive cutting and machine lapping give interference patterns of mechanical damaged surfaces with characteristical features. Lap polished surfaces give Kikuchi pattern and a rel-rod pattern of perfect single crystal which is nearly smooth in the atomic level. Critical remarks are given on the Kikuchi pattern as a feature of perfection of the crystal. Results on the penetration depth of rough defects due to machine lapping are in good agreement with data from literature.     

Zur Versetzungsdichtemessung von GaAs-Einkristallen mit dem automatischen Gefügeanalysator EPIQUANT

The influence of EPIQANT characteristics on measuring error of the etch pit density of GaAs >100< crystals is shown and the determination of the average size of etch pits from the chord length distribution is explained. Special linear analytic measurements in relation to the dislocation array on the crystal section and the size distribution of etch pits yield valuable references to the perfection of crystals.     

Züchtung von (Pb1–xSnx) Te durch Sublimationstechnik

In a horizontal 2-zone resistance furnace nearly ideally formed crystals were grown at the end of an evacuated ampoule, using temperatures between 750 and 720°C, a ΔT of 15 to 10 deg between the rooms of the solution and growth. When applying single heating zone and special conditions good crystals were grown by the use of a quartz rod or a quartz plate as nucleation center. — Finally analytical data on the products of growing are given.