OPTICAL REFLECTION IN PB0.78SN0.22TE DOPED TO 3 AT. PERCENT WITH INDIUM

The spectral dependence of the optical reflection of n-(Pb0.78Sn0.22)( 1-x)InxTe (x = 0.02 and 0.03) and p-Pb0.78Sn0.22Te doped with 3 at. % In and 1.5 at. % Tl has been investigated at T = 300 K. Minima associa ted with plasma vibrations of the free carriers were observed in all t he experimental spectra. The electron density n and the hole density p were estimated by the Kukharskii-Subashiev method. It is shown that t he value of n so obtained is much smaller than its value obtained from the Hall effect only in n-(Pb0.78Sn0.22)(0.97)In0.03Te in which, as h ad been assumed previously, hopping conductivity dominates. This resul t may be viewed as an independent experimental confirmation of the unu sual character of conduction in n-(Pb0.78Sn0.22)(1-x)InxTe solid solut ions with high indium content. (C) 1998 American Institute of Physics. [S1063-7826(98)00509-2].