Temperature effects on valence bands in semiconducting lead chalcogenides

Abstract

Temperature effects on the valence band levels of PbS and PbSe have been studied employing angle-resolved u.v. photoemission. Most of the observed peaks reveal pronounced thermal broadenings and shifts. We show that these effects do not represent a specific feature of the phoroemission process, instead they are ascribed to the thermal broadening of the initial states. The temperature coefficients of the widths of valence levels can be interpreted in terms of constant electron-phonon matrix elements.