Menshikova S. Size effects and transport phenomena in 2D-structures based on PbTe and PbSe semiconductor compounds

Size effects (classical and quantum) in transport phenomena of the semiconductor thin films. The revealing of the classical and quantum size effects in thin semiconductor films of PbTe and PbSe through the study of electrophysical, galvanomagnetic and thermoelectric properties as functions of the film thickness, type of conductivity, charge carrier concentration and technological factors. It is established that under increasing thickness d the kinetic properties of thin films of doped PbTe, stoichiometric PbSe and PbSe doped with Cl exhibit an oscillatory behavior. Such oscillations are attributed to the manifestation of quantum size effect. Oscillation periods calculated within the framework of a model of a rectangular quantum well with infinitely high walls are in good agreement with the experimental ones. The inversion of the conductivity type with changing thickness of PbSe and PbTe doped with Pb or In layers makes it possible to study quantum size effect determined by the behavior of both the electron and hole gases. The calculated thickness dependence of the Seebeck coefficient S(d), using size quantization approximation and taking into account the d-dependence of the Fermi energy and contributions to kinetic coefficients from multiple energetic subbands, for the р-PbTe<Na>, р-PbTe<Pb>, n-PbTe<In> and n-PbSe<Cl> films coincides well with the experimental ones with regard to the oscillation period. The increase of conductivity, electron mobility and Seebeck coefficient with increasing thickness of PbTe and PbSe films is attributed to the manifestation of classical size effect and is interpreted in the framework of the Fuchs-Sondheimer and Mayer theories. It was shown that the fact of classical and quantum size effects manifestation in PbTe and PbSe thin films is independent of charge carrier concentration and conductivity type, film orientation. Thickness oscillations of thermoelectric properties of thin films should be taken into account when preparing materials of n- and p-type conductivity by varying thickness.