Change of light holes valence band in lead-tin telluride films by isovalent substitution of chalcogen atoms

Abstract

Rotational weak-field magnetoresistance measurements at 78 K were used to determine the parameters of the valence band of light holes for Pb 0.8Sn 0.2Te and Pb 0.8Sn 0.2Te 0.98S 0.02 epitaxial films grown on (111)-oriented BaF 2. It was shown that an isovalent substitution of 2% of tellurium atoms by sulphur atoms in solid solution films of lead telluride-tin telluride leads to the decrease of the energy splitting value of valence band valleys Δ σ v from 18 meV to 2 meV. The physical reasons for this phenomenon were analysed. Obtained experimental data were compared with the results of other experiments on photoluminescence and concentration dependencies of thermoEMP coefficient.