The time of flight technique is used to study experimentally the charge-carrier transport in porous silicon. The measured drift mobilities of electrons and holes show a decrease with the reduction of the typical size of structural elements of the porous material. The experimental transient characteristics reveal a strong spatial dispersion of the packet of drifting carriers. The parameters of the dispersion have been determined. The results are analyzed in terms of the dispersion model developed for structurally disordered semiconductors. The similarity and difference in the charge transport between porous silicon and disordered semiconductors are discussed. It is concluded that the dispersion results from the movement of carriers throughout a network of paths different in geometry and electrical properties.

The formation of arrays of Ag nanoparticles from vapor phase on the unheated surface of the amorphous carbon by sequential evaporation of the two portions with decreasing masses has been studied using scanning electron microscopy. The dependence of particle size and their surface density on the amount of evaporated Ag was detected. The precipitate after condensation is in an unstable state: thermal treatment at low temperatures (200-250°C) leads to significant changes and the array goes into a metastable state. This is manifested in the absence of further changes after repeated heat treatment at the same temperature or 100°C higher. It is shown that sequential evaporation of the two portions of the silver with a decrease in mass leads to bimodal distribution of particle sizes in the array.

A comparative study of the transient space-charge-limited current in porous silicon and porous anatase (TiO₂) has been carried out. The room-temperature drift mobilities of electrons in porous silicon and porous anatase, determined from the transit times, are, respectively, 10⁻² and 5×10⁻⁶ cm² V⁻¹ s⁻¹. The specific features of space-charge-limited currents in porous anatase are discussed.

This work is devoted to the morphology and electrical properties optimization of flexible photoanodes based on anodic titanium oxide nanotubular arrays (TiO 2-NTAs) for solar cells with extremely thin absorbing layer (ETA-cells) by TiO 2-nanographite thin composite layer formation on the TiO 2-NTAs surface. First, the carbon doped TiO 2-NTAs were synthesized by annealing of the as-anodized TiO 2-NTAs in argon without foreign carbonaceous precursor. The residual ethylene glycol absorbed on the nanotube wall during anodization serves as the carbon source and the C species are uniformly distributed along the entire nanotube to form the C-TiO 2 NTAs. Further decorating of C-TiO 2-NTAs surface by TiO 2 nanoparticles to form the TiO 2-nanographite (NG) composite layer with high conductivity and increased photoanode effective area showed improved ETA-cells performance.