1548.Manufacturing technique and linearity of characteristics of miniature channel multipliers: M R Aynbund et al, Elektron Tekh Elektronluch Fotoelektr Prib, 2, 1970, 11–15 ( in Russian)

Abstract

The alloying of indium in Bi2Se3 and of cadmium and indium in PbSe and PbTe have been studied using melt-grown crystals containing up to 5 mol per cent of the impurity atoms. In each case, the mixed crystal retains the basic crystal structure type of the host crystal with diminution in the volume of the unit cell. In the lead compounds, the densities of the mixed crystals are in accord with a stoichiometric replacement of cations. The lattice parameter of cadmium-doped PbTe indicates that direct substitution takes place in the octahedral sites of the tellurium atom sublattice, while, in indium-doped PbTe, the indications are that at least one-third of the impurity atoms enter tetrahedral sites. The magnitude of the Hall coefficient of cadmium-doped PbTe is unchanged from that of PbTe itself. This is taken to mean that two s-like states are split off from the valence bands of the crystal to form a high-lying impurity band. An absence of large changes in the Hall coefficient is also found in cadmium-doped PbSe and indium-doped Bi2Se3, where, again, there is a two-electron deficiency in the valence shell of the impurity atom. By contrast, indium is a donor in the lead compounds. In PbSe, it is a strong donor, still consistent with the separation of two states from the valence band of the host crystal. However, in PbTe it behaves as a weak donor, and suggests thereby an ambivalence associated with its distribution between tetrahedral and octahedral sites. The results are discussed in terms of the recent energy band calculations on PbTe by Conklin, Johnson and Pratt.(2)