Evidence for shallow bound states in PbTe

Data are presented showing structure in the magneto-optical absorption of thin films of p-type PbTe, which cannot be explained in terms of free-carrier effects alone. This structure, while having a similar form in many samples, is quantitatively different in samples with different doping. This behavior is strongly suggestive of central cell effects on bound-impurity states rather than of intrinsic many-body effects as recently suggested by McKnight and Drew.