Structure of DX-like centers in narrow-band IV-VI semiconductors doped with group-III elements

This paper presents a study of the structure of the IR reflectance spectra in the Raman spectra in PbTe(In). In the Raman and reflectance spectra of PbTe(In), features are observed at a frequency of omega(0) similar or equal to 120 cm(-1), whose amplitude sharply increases at temperatures T below the temperature where delayed photoconductivity appears, T-c similar or equal to 25 K. A similar feature at a feature sharply increasing for T>T-c similar or equal to 80K. An analysis of the resulting data makes it possible to conclude that, in contrast with classical DX centers in III-V semiconductors, the microscopic structure of the impurity centres in the two-electron (DX-like) ground state does not correspond to an impurity atom shifted from a lattice site, whereas the impurity atom is shifted from a lattice site for the metastable one-electron impurity state. (C) 1998 American Institute of Physics.