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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.

Crystalline silicon is grown onto an amorphous silicon (a-Si) seed layer from a liquid tin solution (steady state liquid phase epitaxy, SSLPE). To investigate the crystallization of embedded a-Si during our process, we adapted Raman measurements for fast mapping, with a dwell time of just one second per single measurement. A purposely developed imaging algorithm which performs point-by-point gauss fitting provides adequate visualization of the data. We produced scans of a-Si layers showing crystalline structures formed in the a-Si matrix during processing. Compared to scanning electron microscopy images which reveal merely the topography of the grown layer, new insights are gained into the role of the seed layer by Raman mapping. As part of a series of SSLPE experiments, which were interrupted at various stages of growth, we show that plate-like crystallites grow laterally over the a-Si layer while smaller, randomly orientated crystals arise from the a-Si layer. Results are confirmed by an in situ TEM experiment of the metal-induced crystallization. Contrary to presumptions, initially formed surface crystallites do not originate from the seed layer and are irrelevant to the final growth morphology, since they dissolve within minutes due to Ostwald ripening. The a-Si layer crystallizes within minutes as well, and crystallites of the final morphology originate from seeds of this layer.

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.

A numerical scheme was developed to compute the thermal and stress fields of the Czochralski process in a quasi-time dependent mode. The growth velocity was computed from the geometrical changes in melt and crystal due to pulling for every stage, for which the thermal and stress fields were computed by using the open source software Elmer. The method was applied to the Czochralski growth of Ge crystals by inductive heating. From a series of growth experiments, we chose one as a reference to check the validity of the scheme with respect to this Czochralski process. A good agreement both for the shapes of the melt/crystal interface at various time steps and the change in power consumption with process time was observed. �� 2019 by the authors. Licensee MDPI, Basel, Switzerland.

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.