Electronic Band Structure and Optical Properties of PbTe, PbSe, and PbS

By using the techniques of wavelength-modulation spectroscopy, we have measured the reflectivity $R\left(\omega \right)$ and the derivative of the reflectivity, $\frac{\left(\frac{1}{R}\right)dR}{d\omega }$, for PbTe, PbSe, and PbS from 1.5 to 6 eV. We have independently calculated the band structure, frequency-dependent dielectric function, density of states, and derivative reflectivity spectrum for all three compounds by the empirical pseudopotential method.