Mössbauer studies of two-electron centers with negative correlation energy in crystalline and amorphous semiconductors

Two-electron tin centers with a negative correlation energy in lead sulfide

“…The equation of electron neutrality of the Pb 1 -x -y Sn x A y S solid solutions generally has the form , (7) where p is the concentration of holes, N A is the con centration of one electron acceptors, and are the concentrations of and centers, respectively.…”

“…However, the first attempts to detect the Mössbauer Ucenters in semiconductors were not successful [3]. The only exception is the impurity tin atoms in chalcogenide vitreous arsenic semiconductors [4][5][6] and in crystalline lead chalco genides [7] for which such centers were identified by the absorption Mössbauer spectroscopy on the 119 Sn isotope. However, the use of absorption variant of Mössbauer spectroscopy makes it possible to study only the materials with high concentrations of the tin impurity (≥4 × 10 20 cm -3 ), while the materials with lower concentrations are of interest.…”