Absorption and photoluminescence in PbTe/Pb1−xEuxTe quantum wells

Photoluminescence (PL) was successfully measured at 4.2 and View the MathML source in a set of PbTe/Pb1−xEuxTe multiple quantum well samples with the well width varying from 2.3 to View the MathML source. From the absorption steps observed in the transmission spectra, the interband optical transition energies between the confined states in the PbTe QWs were determined at temperatures from 5 to View the MathML source. The first absorption step corresponding to the first longitudinal transition correlates very well with the low-energy PL edge. A good agreement is obtained between these values and the electric–dipole transition energies calculated analytically, within the envelope function approximation and the perfect square well model, including strain effects. The energy difference between the first absorption step and the PL edge (Stokes shift) and the PL line width was found to increase with decreasing well width. This result was attributed to the well thickness variation, which has a relatively stronger effect for the narrow wells.