Over the past 30 years, phase change memory materials based on chalcogenide semiconductors have rapidly developed from laboratory prototypes to materials extensively used as functional layers in various devices. First of all, this concerns compounds of the Ge–Sb–Te system, which can be reasonably considered as full-fledged functional materials. The review presents a current view of the control of properties of phase change memory materials by their chemical and structural modification. Both the existing and prospective applications of these materials are highlighted. The discussion of chemical modification focuses on popular dopants such as bismuth, tin, oxygen and nitrogen and also refractory metals. In the discussion of structural modification, the use of laser radiation is considered in detail. Currently, this is a key trend in increasing the operation speed of devices based on phase change memory materials. Data on the formation of periodic surface structures in these materials are highlighted and it is emphasized that this effect could find application in nanophotonics and optoelectronics in the near future. The bibliography includes 336 references

The influence of illumination intensity and p-type silicon doping level on the dissolution rate of Si and total current by photo-assisted etching was studied. The impact of etching duration, illumination intensity, and wafer doping level on the etching process was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Ultraviolet-Visible Spectroscopy (UV–Vis–NIR). The silicon dissolution rate was found to be directly proportional to the illumination intensity and inversely proportional to the wafer resistivity. High light intensity during etching treatment led to increased total current on the Si surface. It was shown that porous silicon of different thicknesses, pore diameters, and porosities can be effectively fabricated by photo-assisted etching on a Si surface without external bias or metals.

The photocatalytic activity of TiO₂ depends on numerous factors, such as the chemical potential of electrons, charge transport properties, band-gap energy, and concentration of surface-active sites. A lot of research has been dedicated to determining the properties that have the most significant influence on the photocatalytic activity of semiconductors. Here, we demonstrated that the activity of TiO₂ in the gas-phase reduction of CO₂ is governed mainly by the desorption rate of the reaction intermediates and final products. This indicates that the specific surface area of TiO₂ and binding strength of reaction intermediates and products are the main factors affecting the photocatalytic activity of TiO₂ in the investigated process. Additionally, it was shown that rutile exhibits higher photocatalytic activity than anatase/rutile mixtures mainly due to its high efficiency in the visible portion of the electromagnetic spectrum.

The influence of Bi doping on the thermal, electrical, and optical properties of Ge₂Sb₂Te₅ thin films was investigated. The existence of two Bi concentration ranges with different influence of dopant on the properties of thin films was established. At low concentrations (0.5–1.0 wt.% of Bi), anomalous deviations of physical properties from monotonous concentration dependences were observed. This effect is explained by the use of percolation theory, where formation of infinite clusters is accompanied by critical phenomena at critical concentrations.