Photoluminescence of a deep level in undoped PbTe

The observation of a gap state in the photoluminescence spectrum of an undoped p-PbTe monocrystalline film grown epitaxially on a [111] BaF2 substrate is reported. A CO2 laser was used for the excitation of electrons into the conduction band. The temperature dependence of the luminescence spectrum has been studied up to 30 K. All the observed features are in agreement with a deep level but it is not yet possible to decide wether the defect level is due to intrinsic defects or to a doping element