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 spe ctra in the Raman spectra in PbTe(In). In the Raman and reflectance sp ectra of PbTe(In), features are observed at a frequency of omega(0) si milar or equal to 120 cm(-1), whose amplitude sharply increases at tem peratures T below the temperature where delayed photoconductivity appe ars, T-c similar or equal to 25 K. A similar feature at a feature shar ply increasing for T>T-c similar or equal to 80K. An analysis of the r esulting data makes it possible to conclude that, in contrast with cla ssical DX centers in III-V semiconductors, the microscopic structure o f the impurity centres in the two-electron (DX-like) ground state does not correspond to an impurity atom shifted from a lattice site, where as the impurity atom is shifted from a lattice site for the metastable one-electron impurity state. (C) 1998 American Institute of Physics.