Study of morphological characteristic ofpor-Si formed using metal-assisted chemical etching by BET-method and fractal geometry

Study of new materials and composites based on porous silicon is of great interest for electronics and microelectronics industry. Functional characteristics of structured layers are closely associated with their morphology properties and treatment conditions correspondently. In this work a porous silicon layers formed by metal-assisted chemical etching (MACE) with the use of gas adsorption-desorption method, scanning electron microscopy (SEM) and fractal geometry have been examined. Specific surface area given by multi-point BET method was about of 7 m₂/g and 13 m₂/g for n-Si and p-Si specimens correspondently. Surface fractal dimension D_s was estimated for p-type mesoporous silicon from BET results using Neimark's thermodynamic approach, the value is D_s=2.86. "Slit islands" Mandelbrot's algorithm was applied for analysis of SEM images and calculations of surface fractal dimension D_s, computation gives D_s = 2.52 for n-Si sample and D_s = 2.84 for p-Si sample. The study testified the fractal nature of porous layers formed by MACE and exhibits correlation between different methods of fractal dimension estimation. The results can be applied for improvement of methods of structured solids characterization.