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The model of electron gas situated on the two-dimensional continual cylindrical surface is suggested to describe a polaron in the single-walled nanotube made of polar material. The problem on weak-coupling polaron is solved using perturbation theory. Analytical expression for the polaron energy shift of the subband is found in the case of bulk phonon approximation and the case when longitudinal optical (LO) phonons are confined on the cylinder's surface. It is shown that in the second case the polaron effect is negligible.

The problem on weak-coupling polaron in the quasi-two-dimensional electron system is solved. Analytical expressions for polaron energy shift of the subband and polaron contribution to the effective electron mass with arbitrary quantum well width are found. The expressions obtained give the well-known values for two- and three-dimensional limiting cases. A comparison of the polaron contribution to the mass with the available experimental data is carried out. Energy relaxation processes of non-equilibrium quasi-two-dimensional electrons with the optic phonon emission are also considered. General analytical expressions for the frequencies of intra-subband and inter-subband transitions for the threshold electron energy are obtained.

The energy spectrum of a weak coupling polaron is considered in a disk-shaped quantum dot. An analytical expression for the polaron energy correction to the ground and the first excited state is calculated using a modified pertubation theory. Anticrossing of the polaron energy levels in the dependence on the quantum dot radius is obtained.

Photoelectric and photovoltaic spectra of Schottky barrier (SB) structures of InSe, GaSe and GaS layered semiconductors (LS) are investigated at quantum energies from the band edge excitons of corresponding materials up to 6.5eV. Spectral dependences of photoconductivity (PC) of photo resistors and barrier structures are strongly different at the quantum energies corresponding to the intermediate type excitons (ITE) observed in these semiconductors. It was suggested that high UV photoconductivity of А 3 В 6 LS is due to existence of high mobility light carriers in the depth of the band structure. It is shown that SB of semitransparent Au-InSe is high sensitive photo detector in UV region of spectra.