Photoemission Investigation of the Band Structure of PbTe

Measurements of the spectral distribution of photoemissive quantum yield and the energy distribution of photoemitted electrons from PbTe for $5.0 \mathrm{eV}<h\nu <11.5\mathrm{} \mathrm{eV}$ are reported. The electron affinity is found to be 4.6±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 ${L_6}^{-}$ and (${L_5}^{-}, {L_4}^{\prime }$) 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.