n-type to p-type crossover in quaternary Bi{sub x}Sb{sub y}Pb{sub z}Se{sub 3} single crystals

We report on the preparation and some physical properties of a quaternary system based on Bi{sub 2}Se{sub 3} codoped with Sb and Pb. Single-crystal samples were prepared using the Bridgman technique and were characterized by measurements of the lattice parameters, electrical resistivity, Hall coefficient, Seebeck coefficient, and thermal conductivity. Atomic emission spectroscopy was used to find the concentration profiles of Sb and Pb along the single-crystalline ingots. Progressive codoping of the Bi{sub 2}Se{sub 3} crystal lattice with Sb and Pb leads to a crossover of the initially n-type conduction to that of the p type. It is assumed that both Sb and Pb enter the Bi sublattice. Physical properties as well as the change in the dominant carrier type are discussed.