On the interband absorption in lead chalcogenides

The optical absorption coefficient K for direct allowed interband transitions between states L and L , respectively, is calculated on the basis of the six‐band model for lead chalcogenides, taking into account the k‐dependence of optical matrix elements. Comparisons are made between theoretical results of the six‐band and two‐band models and experiments. Good agreement is obtained between the calculated and experimental absorption spectrum in the vicinity of the absorption edges. For photon energies ħω > 1.5EG the experiments give higher K than theory. The disagreement is stronger for the six‐band model. The temperature‐ and composition‐dependence of K near the absorption edge are described better by the two‐band than by the six‐band model.