An integral feature of porous silicon and its classification

Porous silicon is currently one of the most studied materials which is used both in the areas traditional for silicon, such as electronics and optoelectronics, and in completely unconventional ones, such as catalysis, energetics, biology, and medicine. The multiple possibilities of the material are revealed due to the fact that its structure can be radically different depending on the properties of the initial silicon and the methods of obtaining porous phases. The use of any material inevitably leads to the need to classify its various forms. The purpose of the article was to find the most significant parameter that can be used as the basis for the classification of porous silicon.Historically, the terminology defined by the IUPAC pore size classification has been used to classify porous silicon. Due to the authority of IUPAC, many researchers have considered this terminology to be the most successful and important, and the radial pore size has often been regarded as a main parameter containing the most important properties of porous silicon. Meanwhile, the unique properties and practical application of porous silicon are based on its developed inner surface. The method of nitrogen porosimetry, which is simple in its practical implementation, is often used in scientific literature to determine this value.The most suitable integral parameter for the classification of porous silicon, regardless of its structure and morphology, is the total specific internal surface (cm-1) that can be relatively easily established experimentally and is of fundamental importance for almost all applications of porous silicon. The use of this value does not exclude the use of other parameters for a more detailed classification