Assessment of changes in the texture of the silicon surface under the influence of a magnetic field and high-temperature plastic deformation using fractal analysis

Materials based on silicon are widely used in energy, electronic devices, solar cells, optoelectronics, and the electronics industry. A current challenge is the controlled use of these materials in technologies under mechanical loads, radiation, and magnetic fields. The aim of the study is to investigate the change in the surface texture of silicon under the influence of a magnetic field and high-temperature plastic deformation using fractal analysis. The material for the study consisted of n-Si monocrystalline silicon wafers grown by the Czochralski method (Si-CZ), with controlled damage applied to the surface using a diamond indenter. The study employed a method to investigate dislocation movement in silicon single crystals under high-temperature plastic deformation. The experimental technique combines several materials science methods: deformation by the four-point bending test, annealing, chemical etching, and microscopy. In addition to high-temperature plastic deformation, silicon was treated in a magnetic field. The sample was placed between the poles of an electromagnet to create a magnetic field. The magnetic induction vector was perpendicular to the induced scratch. The analysis and description technique combines visual observation of photographs and fractal analysis of microimages of the chemically etched surface of silicon. Within the framework of fractal analysis, fractal dimension and lacunarity indicators were determined, which describe the unevenness and complexity of the dislocation structure of the surface. The obtained images revealed numerous dislocation exits on the surface located around the artificially created scratch, as well as changes in the surface texture. Magnetic treatment leads to the segregation of silicon atoms and impurities at the surface and the formation of a granular structure on the wafer surface. In this case, the fractality of the surface of the samples increases, while lacunarity decreases. It has been shown that under the influence of a weak magnetic field, the stabilization or blocking of the movement of already existing dislocations is possible. After turning off the field, the energy in the system is insufficient for these defects to activate and begin to move even after a second round of annealing and load. This behaviour allows for the use of sample treatment in a magnetic field to obtain defect-free silicon structures.