Photoemission Investigation of the Band Structure of PbTe

Abstract

Measurements of the spectral distribution of photoemissive quantum yield and the energy distribution of photoemitted electrons from PbTe for $5.0 \mathrm{eV}<h\ensuremath{\nu}<11.5 \mathrm{eV}$ are reported. The electron affinity is found to be 4.6\ifmmode\pm\else\textpm\fi{}0.3 eV. Regions with high density of states are located 0.7 and 1.2 eV below the valence-band maximum and assigned to the (${{L}_{4}}^{+}, {{L}_{5}}^{+}$) and ${{L}_{6}}^{+}$ symmetry points, respectively. By using the photoemission data and Cardona and Greenaway's optical data, the ${{L}_{6}}^{\ensuremath{-}}$ and (${{L}_{5}}^{\ensuremath{-}}, {{L}_{4}}^{\ensuremath{'}}$) conduction-band points are located approximately 1.3 eV above the valence-band maximum. A high-density point is found 2.4 eV below the valence-band maximum. Evidence is presented that this high-density point is not due solely to structure near the $L$ point.