Role of intervalley scattering in the radiative recombination in Pb1 − xEuxTe alloys (0 ≤ x ≤ 1)

Measurements of the photoluminescence from epitaxial layers of Pb1 − x Eu x Te alloys with 0 ≤ x ≤ 0.32 are carried out. It is found that the luminescence intensity decreases with increasing Eu content and, already for x as low as about 0.1, drops by more than one order of magnitude. No luminescence is observed for 0.2 0.85, optical transitions also take place with the participation of the X valley; in this case, the emission is governed by the formation of magnetic polarons. The temperature dependences of the band gap are determined for 0 ≤ x ≤ 0.11. These dependences have a wide linear region characterized by a positive dE g /dT coefficient, which decreases with the Eu content to become negative in pure EuTe.