IDENTIFICATION OF ONE-ELECTRON AND 2-ELECTRON IMPURITY CENTERS IN SEMICONDUCTORS BY MOSSBAUER-SPECTROSCOPY

Mossbauer spectroscopy based on the isotopes Fe-57 and Sn-119 has been used to demonstrate how the charge state of iron impurity atoms in II I-V compounds (Gap, GaAs), as well as that of tin impurity atoms in le ad and indium chalcogenides (PbS, PbSe, PbTe, In2S3) depends on the po sition of the chemical potential in the band gap of the semiconductor. The neutral and ionized states of the impurity atoms are identified. It is shown that iron impurity atoms in III-V compounds form single-el ectron levels and that tin impurity atoms in lead and indium chalcogen ides form two-electron levels. The sign of the correlation energy for the two-electron tin centers is determined. (C) 1996 American Institut e of Physics.