Experiments revealed that Bi had an amphoteric doping effect upon epitaxial films, in that the dopant atoms could assume various positions in the lattice. The distribution of Bi atoms among the sub-lattices was found to depend upon the contents of Pb and Se in the vapor. The experimental data indicated that Bi in Pb sites was a singly ionized donor, while Bi in Se sites was a triply ionized acceptor. It was shown that doping with amphoteric Bi was an effective tool for the study of defect generation in the present material. An increase, in the amount of Se in the vapor, generated vacancies in the cation sub-lattice. Excess Pb initially took up interstitial positions. The formation of vacancies in the Se sub-lattice was observed only in the presence of a Pb excess which was of the order of 1019 to 2 x 1019/cm3.

V.A.Zykov, T.A.Gavrikova, S.A.Nemov: Fizika i Tekhnika Poluprovodnikov, 1995, 29[2], 309-15 (Semiconductors, 1995, 29[2], 154-7)