Excitonic absorption lines of PbS in a CdS–PbS composite

The spectral dependences of transmission, absorption, and reflection in CdS–PbS semiconductor layers, which are promising for the development of photodetectors and emitters in the region of an atmospheric-transparency window, were studied. It has been established that a series of thin lines are observed in the infrared spectrum on an absorption edge of the narrow-gap phase (PbS). A method for identification of exciton series was used, and exciton-binding energy $E_{ex}$, exciton concentration $N$, and value of valence-band splitting $(\Delta E_{v})$ were determined.