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The influence of different melt streams on the distribution of phosphorus in multi-crystalline silicon ingot was studied. Phosphorus-doped multi-crystalline silicon (mc-Si) ingots were directionally solidified using travelling magnetic fields (TMF) to alter axial phosphorus profiles. Resistivity distributions in the crystallized n-type ingots were measured along the ingot length. Different Lorentz forces were applied in order to enhance melt stirring and with that to transport phosphorus more rapid towards the melt surface. A new rectangular setup was developed, which enables simultaneous directional solidification of 4 G0-sized mc-Si ingots (80 x 80 x 60 mm3) under the influence of TMF. 900 g ingots with different initial level of phosphorus doping were grown, and dopant concentrations in ingots were related to stirring intensities. The phosphorus evaporation rate significantly affects axial dopant profile of mc-Si material, thus this approach can be used as a powerful tool to control and tailor resistivity distribution along phosphorus-doped mc-Si ingots.

The crucible free growth of dislocation free respectively low defect single crystals on large diameter silicon seeds without using the common Dash technique was investigated. A promising concept to reach this aim was to reduce the thermal gradients and stresses. Therefore, a combination of RF- and MF heating, additionally to the standard FZ setup, was used by implementation of a further coil which is surrounding the 4 inch diameter seeds. The heat dissipation conditions, the growth velocity and the ratio between RF- and MF power were varied. Crystals were grown with a total length up to 120 mm. After 90 mm of single crystalline growth the crystals became polycrystalline. All grown crystals, independent of the seed structure or preparation procedure, developed a dislocation network during heating already before melting the seed surface and growth start. By noticeable reduction of the thermal stresses the single crystalline status could be maintained for a certain distance and an immediate transition to the polycrystalline growth could be avoided.

Residual stress is a key feature which has to be taken into account in all steps of fabrication and processing of semiconductor materials and devices. The photo-elastic microscope SIREX (Scanning Infrared Stress Explorer) measures the depolarization of the light of an infrared laser probe caused by stress-induced birefringence in the sample. Subsequently, a map visualizes the in-plane optical anisotropy induced by stress. Hence, the system is applied as non-destructive tool to map stress distributions with high lateral resolution (3µm) and highest possible stress sensitivity (0.1 kPa). The so-called multi-polarization analysis results in maps of the in-plane maximum shear stress magnitude Δσ and the direction of the principal stress components. These maps can reveal the local stress fields of buried defects and their alignment in distinctive crystallographic directions. The fields are usually at least one order of magnitude larger in extension than the related defects themselves. Examples of extended defect structures in different crystalline semiconductor materials are presented in this paper. The emphasis has been put on line-shaped structures such as slip lines and twins which are partly accompanied by either tensile or compressive point-like stress sources. These structures are showing model characteristics for developing formal procedures of data and image processing under industrial conditions.

We performed a numerical feasibility study of the application of the lateral photovoltage scanning (LPS) method to detect doping inhomogeneities (striations) in GaAs. Those striations follow the shape of the crystallization front, enabling its visualization. The obtained results allow direct validation of simulated temperature distributions in GaAs crystals. Our simulations revealed that realistic laser powers lead to LPS signals on the order of nanovolts. The actually used LPS measurement setup detects voltages at microvolt scale. So in order to build practical setups, one needs to either use better voltage detection devices or improve the method itself.

Dewetting is a ubiquitous phenomenon which can be applied to the laser synthesis of nanoparticles. A classical spinodal dewetting process takes place in four successive states, which differ from each other in their morphology. In this study all states are revealed by interaction of pulsed nanosecond UV laser light with thin gold layers with thicknesses between 1 nm and 10 nm on (100) silicon wafers. The specific morphologies of the dewetting states are discussed with particular emphasis on the state boundaries. The main parameter determining which state is formed is not the duration for which the gold remains liquid, but rather the input energy provided by the laser. This shows that each state transition has a separate measurable activation energy. The temperature during the nanosecond pulses and the duration during which the gold remains liquid was determined by simulation using the COMSOL Multiphysics® software package. Using these calculations, an accurate local temperature profile and its development over time was simulated. An analytical study of the morphologies and formed structures was performed using Minkowski measures. With aid of this tool, the laser induced structures were compared with thermally annealed samples, with perfectly ordered structures and with perfectly random structures. The results show that both, structures of the laser induced and the annealed samples, strongly resemble the perfectly ordered structures. This reveals a close relationship between these structures and suggests that the phenomenon under investigation is indeed a spinodal dewetting generated by an internal material wave function. The purposeful generation of these structures and the elucidation of the underlying mechanism of dewetting by short pulse lasers may assist the realisation of various technical elements such as nanowires in science and industry.

High Purity Germanium (HPGe) crystals are indispensable for radiation detection and fundamental research. Among other applications they will be used in the Large Enriched Germanium Experiment for Neutrinoless double beta Decay (LEGEND) experiment for the search of neutrinoless double beta decay of 76 Ge. Ongoing research activities are done in collaboration with members of the existing GERDA experiment. In this context the Leibniz-Institut fur Kristallzuchtung (IKZ) is engaged in the development of HPGe Czochralski crystal growth including purification and characterization of the material. The Ge starting material is purified in a horizontal multi-zone furnace. Two inch Ge single crystals were grown by the Czochralski method and analyzed with respect to electrically active impurities by means of Hall-effect measurements and Photo-thermal Ionization Spectroscopy. The dislocation density is assessed by combining defect etching and optically microscopy imaging. Lateral Photovoltage Scanning is applied to visualize doping striations, which bear information on the shape of the solid–liquid phase boundary during growth.