Properties of iron-doped Sb2Te3 single crystals

Iron-doped Sb2Te3 single crystals (C-Fe = (0-9.5) x 10(19) atoms/cm(-3)) we re prepared from elements of semiconductor purity using a modified Bridgman method. The samples of these crystals were characterized by means of X-ray diffraction analysis, measurements of the reflectance in the plasma resona nce frequency range omega (p), of the Hall constant R-H(B parallel to c) an d electrical conductivity sigma (perpendicular toc). It was found that the incorporation of Fe atoms into the Sb2Te3 crystal lattice reduces the volum e of the unit cell; the values of omega (p) and RH(B parallel to c) (i.e. t he concentration of holes) increase and the values of sigma (perpendicular toc) decrease with increasing iron content. The observed increase in the ho le concentration is explained as due to the incorporation of Fe atoms into the Sb-sublattice creating thus substitutional defects of Fe'(Sb). The decr ease in the electric conductivity is associated with a decrease in the hole mobility.