Far-infrared reflection spectra of PbSrSe thin films grown by molecular beam epitaxy

We report the far-infrared (FIR) reflection measurements of Pb 1- x Sr x Se thin films with different Sr concentrations grown by molecular beam epitaxy on BaF 2 substrates. Sr composition and lattice parameter have been assessed by x-ray diffraction. By fitting the FIR reflection spectra and by comparison with the results of binary PbSe and SrSe thin films, both PbSe-like and SrSe-like optical phonon reflection bands in ternary PbSrSe thin films have been identified. Also, the carrier concentration and mobility of PbSrSe thin films have been extracted from the theoretical calculation of the reflection spectra, and are found to be in agreement with reported results from Hall measurements.