Growth of Pb 1− xSn xTe ( x≈0.12) epitaxial layers by temperature difference under controlled vapor pressure liquid-phase epitaxy

Abstract

Pb 1− x Sn x Te ( x≈0.12) liquid-phase epitaxial layers have been grown by the temperature difference method under controlled vapor pressure (TDM–CVP) using Pb solvents on PbTe substrates at temperatures 490°C and 600°C. The grown layers are usually n-type, and the optimum Te vapor pressure where the carrier concentration becomes minimum is 3.1×10 −3> P Te>1.4×10 −3 Torr for T g=600°C, and 3.1×10 −5 >P Te >1.4×10 −5 Torr for T g=490°C. The activation energy of the optimum Te vapor pressure for Pb 1− x Sn x Te ( x≈0.12) is 2.38 eV, which is larger than the activation energy for PbTe, 2.12 eV. Two different types of etch pits are observed on Pb 1− x Sn x Te ( x≈0.12) layers. The density of the smaller size etch pits tends to become minimum at the optimum Te vapor pressure, while the larger size etch pits are dominantly observed at the vapor pressure region above the optimum vapor pressure. This tendency and lower electron mobility suggest defect aggregation taking place above the optimum vapor pressure.