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Interband magneto-optical studies are reported on strained and unstrained films of PbTe grown on BaF2, NaCl and PbTe substrates. By a careful orientational study of the magneto-absorption of these films it has been possible to deduce an accurate set of band parameters for PbTe, using the six-band Mitchell-Wallis k.p model. It is demonstrated that the inbuilt strain in the layers is an important parameter, which can cause changes in both the bandgap, and the momentum matrix element coupling the L3-6-and L1+6+bands. Both uniaxial and hydrostatic components of strain are shown to be present, and these are used to deduce the deformation potentials for PbTe. The anisotropy of the conduction and valence bands is shown to be independent of the strain.

A versatile atomic force microscope (AFM), which can be installed in a scanning electron microscope (SEM), is introduced. The flexible design of the instrument enables correlated analysis for different experimental configurations, such as AFM imaging directly after nanoindentation in vacuum. In order to demonstrate the capabilities of the specially designed AFM installed inside a SEM, slip steps emanating around nanoindents in single crystalline brass were examined. This example showcases how the combination of AFM and SEM imaging can be utilized for quantitative dislocation analysis through the measurement of the slip step heights without the hindrance of oxide formation. Finally, an in situ nanoindentation technique is introduced, illustrating the use of AFM imaging during indentation experiments to examine plastic deformation occurring under the indenter tip. The mechanical indentation data are correlated to the SEM and AFM images to estimate the number of dislocations emitted to the surface.

The dependence of the magnetic freeze-out and the sign change of the Hall effect on impurity concentration, compensation and temperature has been investigated under uniaxial stress up to 4 kbar in the magnetic field range of 1–10 Tesla. Both the transverse and longitudinal conductivity are strongly increased by an uniaxial stress of some kbar. While the zero-stress results were described by a quantum transport theory including the effect of the nonparabolicity of the conduction band on ionized impurity scattering consistently, this theory fails to reproduce the stress dependence of the conductivity tensor.

X-ray rocking curves of (001) CdTe epilayers on (001) GaAs grown by hot wall epitaxy have been measured. The dependence of the rocking curve width on sample thickness and substrate preparation was studied. Increasing the thickness of the CdTe layer results in a reduction of the rocking curve width. The substrate preheating temperature significantly influences the width of the rocking curve of the CdTe epilayer. A model which considers the effect of an interface layer at the CdTe / GaAs interface is proposed in order to explain the experimental data.

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Nuclear transmutations by thermal neutrons are used to control the doping characteristics of n-InSb in a systematic way. The concentration of the produced donors is determined by an analysis of Hall effect and mobility measurements in a temperature range where ionized impurity scattering dominates. This concentration agrees very well with the additional donor concentrations calculated from the total flux of the thermal neutrons. Durch Kernumwandlung mittels thermischer Neutronen konnte die Dotierung von n-InSb systematisch variiert werden. Die Konzentration der erzeugten Donatoren wurde durch eine Analyse von Halleffekt- und Beweglichkeitsmessungen in einem Temperaturbereich bestimmt, in dem Streuung an ionisierten Storstellen dominiert. Mit Werten, die aus dem totalen Flus der thermischen Neutronen bestimmt wurden, konnte sehr gute Ubereinstimmung erzielt werden.

Pb1-xEuxTe single-crystalline epitaxial films were prepared by a modified hot-wall technique. The structural properties were checked by X-ray diffractometry and microprobe analysis. Single-phase material with up to 5% Eu content was produced. Transport properties were investigated between 5 and 300K yielding electron concentrations and mobilities comparable with those of PbTe epitaxial layers. The direct energy gap and its dependence on Eu content as well as on temperature were determined by optical absorptance and reflectance measurements using Fourier transform spectroscopy. This technique also yielded the phonon and free-carrier contributions to the dielectric function in the far-infrared region. Intraband magneto-optical experiments were carried out in Faraday and Voigt geometries in order to obtain information on the effective masses and their anisotropies. For the interpretation of these reflectance and transmittance data as a function of frequency and magnetic field, a Drude model calculation for this many-valley system was performed. For the Voigt geometry in particular, the dielectric tensor and the appropriate complex refractive indices for the ordinary and extraordinary modes are treated in detail. The Shubnikov-de Haas data reveal that the L valleys are not occupied by the carriers equally. Magneto-optical studies between 5 and 50K confirm these findings. Possible sources for the carrier repopulation and its change with temperature are discussed.

At liquid helium temperatures a change of the sign of the Hall effect of n-InSb is observed in the magnetic freeze-out regime. The experimental examination of possible explanations and their discussion show that only the contribution of the asymmetric impurity scattering (“skew scattering”) to the Hall effect explains the observed systematic behaviour of the sign change. Bei Temperaturen des flussigen Heliums beobachtet man in n-InSb im Bereich des magnetischen Ausfrierens einen Vorzeichenwechsel des Halleffekts. Die experimentelle Uberprufung verschiedener Erklarungsmoglichkeiten und deren Diskussion zeigt, das nur der Beitrag der asymmetrischen Fremdionenstreuung (“skew scattering”) zum Halleffekt die experimentell beobachtete Systematik des Vorzeichenwechsels erklaren kann.

Recently, contradicting results concerning magnetotransport experiments on n-InSb at liquid helium temperatures have been reported by various authors. The authors' experiments show that the assumption of the existence of a conducting surface layer due to soldering of tin contacts to the samples is not valid. Experiments on samples treated by careful etching procedures have proven the sign change of the Hall effect and the saturation of the transverse magnetoresistance to be bulk effects.

At a temperature of 0.37 K structures are observed in the current–voltage characteristics of n-InSb (NI = 3 × 1015 cm−3) at electric fields in the range 1 to 10 V/cm and at magnetic fields above 7 T. This is related to the impact ionization of excited impurity levels. The disappearence of this structure at lower magnetic fields and at higher temperatures is explained by an increasing broadening of the impurity energy levels with increasing temperature. Bei einer Temperatur von 0,37 K werden in der Strom–Spannungs-Kennlinie von n-InSb (NI = 3 × 1015 cm−3) Strukturen im elektrischen Feldbereich 1 bis 10 V/cm und in Magnetfeldern uber 7 T beobachtet. Dies wird mit der Stosionisation von angeregten Fremdatomniveaus in Bezug gebracht. Das Verschwinden dieser Strukturen bei niedrigeren Magnetfeldern bzw. hoheren Temperaturen wird durch eine Zunahme der Verbreiterung der Fremdatomenergieniveaus erklart.

Elastic strain significantly affects the electric and optical properties of PbTe/Pb1-xSnxTe - strained-layer superlattices. In the range of 10 - 350K the temperature dependence of the elastic strain present in these superlattices was measured by double-crystal x-ray diffraction. For superlattice periods smaller than 100nm High-angle x-ray interferences were observed. Using a novel method, which makes use of the High-angle interferences both for symmetrical as well as for asymmetrical reflections in a theta-twotheta scan with a narrow detector slit, the relative inclination of equivalent lattice planes due the elastic strain was measured. The components of the complete strain tensor of the constituent layers can be determined seperately even if their unstrained lattice constants are not known with sufficient accuracy as is the case in ternary and quaternary compounds. The lattice mismatch of up to 0.4% for Sn-contents smaller than 20% was found to be accommodated almost completely by elastic misfit strain. The amount of strain is shared between the constituent layers inversely to their relative thicknesses as long as the superlattice as a whole is much thicker than the buffer layer. Below room temperature an additional temperature dependent tensile strain due to differnt thermal expansion coefficients of the film and the BaF2-substrate is measured quantitatively.

X‐ray rocking curves of (100) and (111) oriented CdTe epilayers grown by hot wall epitaxy on (100) GaAs substrates have been measured. Our results indicate that the number of extended defects increases with thickness in (111) CdTe epilayers but decreases with thickness in (100) CdTe epilayers. The distortion of the GaAs surface induced by the CdTe epilayer is determined from comparative measurements of the rocking curve of the covered and uncovered GaAs substrate.

The strain in IV-VI semiconductor superlattices (SL) introduces qualitatively new features, originating from the many-valley band structure, not found in III-V SL systems. For the PbTe/PbSnTe system the misfit and substrate induced strain in the constituent layers is determined by X-ray diffractometry. The SL band structure, recently calculated by the envelope function approach is strongly modified by this strain. By varying the thickness ratio of the constituents and thus the strain, the electronic properties can be influenced accordingly.

A stress apparatus is reported which allows us to apply forces up to 300 N to solids perpendicular to the field in a superconducting magnet. This configuration is necessary to study stress dependences of transverse magneto‐transport effects and magneto‐optical properties in Faraday geometry. The usefulness of the apparatus is demonstrated by Hall effect and transverse magnetoresistance measurements in n‐InSb as well as far‐infrared cyclotron resonance experiments on n‐Ge.

A change of the sign of the Hall coefficient is observed in n-InSb with carrier concentrations from 5 x 1013 to 1015 cm−3 at liquid helium temperatures and magnetic fields above some 20 kG. The influence of doping is investigated systematically. The sign change is discussed in the light of the anomalous Hall effect due to spin-orbit interaction.

Since the early magnetooptical investigations of IV-VI compounds by Palik et al. [1] it has been known, that epitaxially grown single crystalline films on various alkali halide substrates exhibit strain effects. These are caused by the difference in the temperature dependence of the thermal expansion coefficients of semiconductor film and substrate. This mismatch leads to a tetragonal(on (100) oriented substrates: NaCl/kCl) or rhombo-hedral (on (111) oriented substrates: BaF2, CaF2) distortion [2]. e.g. in Ref. [1] it was shown that the energy gap of PbTe/NaCl is different from bulk PbTe at low temperatures. Despite these shortcomings heteroepitaxial semiconductor films are of considerable interest for devices like infrared detectors.