Influence of potential barriers on the thermoelectric properties of PbTe thin films

The PbTe films, 0.4-3 μm thick, were formed on different substrates by the method of flash evaporation. The samples had a single crystal structure with blocks and the angle of misorientation was ⩽1°. The dimensions of the blocks were ~1 μm for the films on mica. Block boundaries were a system of edge dislocations. On one side of each dislocation there was a region of compression and on the other a region of dilatation. Regardless of the sign of the deformation potential, potential energy relief is formed near a block boundary. Estimates obtained using parameters of bulk PbTe have shown that the energy barrier can reach 0.1 eV. The electrical conductivity σ, Seebeck coefficient S, Hall coefficient R, and Nernst-Ettingshausen coefficient Q were measured in the 80-500 K range. A comparison with bulk PbTe single crystals with the same charge concentration indicates that the films were characterized by a higher parameter S²σ. This difference was attributed to energy-selective carrier scattering by potential barriers. The potential relief in PbTe thin films was obtained using an electron-beam induced current. Doping of PbTe films with certain impurities can be used to control their barrier properties