Modulationsabhängige Inklination im Fernfeld von GaAs-Lumineszenzdioden vom Fabry-Perot-Typ

The dependence of the transverse far field intensity distribution of GaAs lightemitting diodes on the ac-frequency is studied. The used four-layer-step-discontinuity of the dielectric constant influenced by the free-carrier absorption is modified in that the region of light creation and the wave guide region are assumed to be separate. The so calculated inclination of the maximum far field intensity direction in comparison with the plane normal to the light emitting surface of the diode decreases with increasing modulating frequency. The frequency influence on the phase homogeneity of the radiated light is shortly mentioned.     

Über die Flächenverteilung von Dekorationskeimen in der Umgebung von Versetzungen

Cleaved and evaporated faces of KCl:Me²⁺ single crystals were decorated with gold. The surface distribution of the decoration grains was investigated electron-microscopically. In the surroundings of the points of emergence of dislocations characteristic changes in the density distribution of the gold grains could be observed. They are described and discussed.     

Zum Wachstum von AIII-BV-Verbindungen aus nichtstöchiometrischen Schmelzen (III) Untersuchungen zur Flächenmorphologie homoepitaktischer GaAs-Schichten

The morphology of a surface with the formation of GaAs-layers from Ga solutions is caused by the primary formation of characteristic holes. The reason for the origin of such holes is explained by small stresses resulting from small lattice mismatches.     

Änderung von Verformungseigenschaften der intermetallischen Verbindung MgZn2 im Homogenitätsbereich

Solid solution softening within the range of homogeneity of the intermetallic compound MgZn₂ appears to be due to variations of the dislocation density. This has been shown by independent measurements of dislocation velocity and dislocation density.     

Ein Dielektrizitätskonstanten-Meßplatz zur Untersuchung optischer Kristalle im Mikrowellenbereich

This article reports on a dielectric constant measuring apparatus which operates in the 3 cm microwave range using the method of resonance. Evaluation formulae and limits of the method are indicated. Finally, we will give the values ϵ′ and ϵ″ of optical crystals belonging to different treatments.     

Abbildungserscheinungen an Isolatorschichten im Elektronenspiegelmikroskop unter stationären Aufladungsbedingungen

Typical phenomen in imaging non-covered dielectric layers under stationary conditions of charging in the electron mirror microscope are described, and their dependence on the imaging parameters is given. A special characteristic is the stabilization of the surface potential of the insulating layer by charging in the range of about 0V. Basing on observations of the contrast balance on potential steps the surface potential of the insulating layers is measured. For the investigated fluorocarbon films the stabilizing surface potential amounts to about – 2 V. From this value the current of positive charge carriers on the surface of the specimen is estimated.     

Zur Entstehung des Kornkontrastes bei chemisch geglänztem Zinn im Elektronenrastermikroskop

Electron probe investigations of bulk metallic chemically polished tin show a grain contrast in absorptive, reflective and in x-ray mode. By observation of cathodoluminescence and by measuring the concentration of oxygen it is possible to state that the grain contrast is not produced by anomalous absorption effects but by oxidized thin surface layers. The general influence of surface layers on the production of the orientation contrast is discussed.     

Bildung von paramagnetischen Defekten in SiO2-Glas nach Oberflächenbehandlung im Niederdruckplasma

Low pressure plasma treatment of SiO₂-glass produces paramagnetic defects in SiO₂ volume. The defects are similar to those created in quartz (glass or crystal) by neutrons or γ-radiation. As a cause of defect formation taking place only in glassy and not in crystalline samples plasma radiation is proved. From dependence of defect concentration on conditions of formation (plasma parameters, time of treatment) a complex mechanism of formation will be concluded. The depth distribution of defects refers to their diffusion in SiO₂ volume.     

Die Abhängigkeit der Röntgenemissionsspektren vom chemischen Bindungszustand und der kristallographischen Orientierung der Proben und die Bedeutung dieser Effekte für mikroanalytische Untersuchungen

It is shown that also more subtle X-ray spectroscopic effects such as the dependence of the spectra on chemical bond and crystallographic orientation (of monocrystalline samples) can be measured by means of modern electron microprobe analysers because of their high resolving power. When neglected these effects can falsify microanalytic measuring data, but they also can widely extend their information content which is demonstrated at hand of examples. Some possibilities of applications of the electron microprobe analysers for fundamental investigations in the field of X-ray spectroscopy (e. g. energy band structure of solids) are demonstrated and specific advantages of their use are referred to.     

Bestimmung der Lage der Wassermoleküle im Kieserit MgSO4 · H2O mit Hilfe der magnetischen Protonenresonanz

Investigations on proton magnetic resonance of Kieserit are performed using various crystals of essentially better quality than in former experiments. Measuring single crystals the same rather high value of the proton-proton-distance inside the crystal water molecule resulted; the data on the orientation of the proton-proton-line, however, are different from those formerly determined, attributed to the high crystal quality. The second moment of the PMR signal of Kieserit crystal powder is found to be independent on temperature in the range of nearly four hundred degree. This behaviour supports the value of the intramolecular proton-proton-distance, given above. The results demonstrate the existence of „branching”︁ hydrogen bonds and are consistent with other properties of Kieserit. The fine structure occurring in the spectra is interpreted as an effect of the intermolecular magnetic dipole-dipole-interaction between the water protons.     

Die Berechnung von Kriterien für die Abscheidung reiner Phasen binärer Systeme beim chemischen Transport und der Transport im System Cu-O

A thermodynamical analysing method is described of the deposition of binary solids AB_x, which specially takes into account the influence of the coexistence equilibria in the A—B-system. This analysis is applicated to the Cu—O system. It permits to calculate the conditions, under which Cu₂O is deposited without deposition of any other phases. The deposition of cuprous oxide by CTR-techniques is investigated using hydrogen halides as transport media. The experiments result in the growth of Cu₂O-monocrystals (2 × 2 × 2 mm) only if HCl is used as transport medium. Using HI the simultaneous deposition of Cu₂O and Cu is observed.     

Zur anisotropen Dilatation von Fe3S4-Kristallen im elektrostatischen Feld

Synthetic crystals of Fe₃S₄ (greigite, spinel type, lattice constant 9.87 ÅU) extend by about 0.05 ÅU in an electrostatic field (field strength 860 volts · cm⁻¹) along the [111] axis in preference to any other directions. This property to be easily deformed makes it difficult to develop this crystallite (grain size about 300 ÅU) to a single crystal. It transforms into hexagonal pyrrhotite when cultivating it for crystal growth.