Ballistic Transport Phenomena in Nanostructures of Paraelectric Lead Telluride

This is a review of our recent developments in the physics of lead telluride nanostructures. PbTe is a IV{VI narrow gap paraelectric semiconductor, characterized by the huge static dielectric constant " > 1000 at helium temperatures. We nanostructurized this material by means of e-beam lithography and wet chemical etching of modulation doped PbTe/Pb1ixEuxTe quantum wells. Magnetoresistance measurements performed on the nanostructures revealed a number of magnetosize efiects, conflrming a ballistic motion of the carriers. The most important observation is that the conductance of narrow constrictions shows a precise zero-fleld quantization in 2e 2 =h units, despite a signiflcant amount of charged defects in the vicinity of the conducting channel. This unusual result is a consequence of a strong suppression of the Coulomb potential ∞uctuations in PbTe, an efiect conflrmed by numerical simulations. Furthermore, the orbital degeneracy of electron waveguide modes can be controlled by the width of PbTe/Pb1ixEuxTe quantum wells, so that unusual sequences of plateau conductance can be observed. Finally, conductance measurements in a nonlinear regime allowed for an estimation of the energy spacing between the one-dimensional subbands. PACS numbers: 72.80.Jc, 73.21.Hb, 73.23.Ad, 77.22.Ch