Effect of plastic deformation on the transport phenomena in Pb_0.95Sn_0.05Se single crystals

Abstract

The temperature dependences of the Hall coefficient and specific resistance were investigated in the range 77–350 K for plastically deformed Pb_0.95Sn_0.05Se single crystals. The undeformed samples had a hole conductivity. It was found that the dislocations being introduced under a single-slip mode had a donor effect. As the deformation degree increases, the acceptor action is compensated, which leads to the inversion of conductivity type in a narrow dislocation concentration N _D interval with a subsequent rise in the electronic conductivity. The results can be explained by a mechanism of intrinsic point-defect formation during the slip process of the screw and split edge dislocations with jogs. The Hall mobility investigations show that, in the deformed crystals, scattering by both phonons and lattice statistical defects is a factor. The role of these defects increases with increase in the dislocation concentration and decrease in the temperature. The temperature dependence of mobility decays and flattens out below some temperature (increasing with increasing N _D). On the basis of the data obtained, it was shown that, because of the dielectric constant and carrier concentration values, scattering by a dislocation deformation potential is the dominating mechanism. In the low-deformation samples having a hole conductivity, a sign inversion was discovered for the Hall coefficient as the temperature increases. This may be explained by the presence of a dislocation acceptor zone in the valence zone. The transitions to the empty states of this zone due to inelastic scattering by the longitudinal optical phonons lead to a decrease in the hole mobility by a factor of two to three.