Electrical properties of Pb1-xSnxTe layers with 0⩽x⩽1 grown by molecular beam epitaxy

In this work, the electrical properties of Pb1−xSnxTe epitaxial layers with Sn composition covering the whole range were investigated. The samples were grown on (111)BaF2 substrates in a molecular beam epitaxy system using PbTe, SnTe, and Te solid sources. As the alloy composition varies from PbTe to SnTe, the hole concentration increases exponentially from 1017 to 1020 cm−3 for Te-rich sources and from 1017 to 1019 cm−3 for stoichiometric ones. The resistivity of the samples, which depends mainly on their hole concentrations, shows an exponential dependence on the temperature with a slope which decreases as x goes from 0 to 1. For all Pb1−xSnxTe samples with x in the range of 0.35–0.7, the resistivity curve shows a very well defined minimum at low temperatures. This anomalous behavior is supposed to be related to the band crossing, where the energy gap temperature coefficient changes sign. The temperatures where the minimum in the resistivity occurs only agree with the ones predicted by the band inversion model around x=0.4, exhibiting a large deviation to lower temperatures as x increases.