High power factor and mobility of single crystals of Bi2Se3 induced by Mo doping

Abstract

Few binary compounds attract as much attention as Bi2Se3. In addition to its use as thermoelectric, it has become one of the prototype 3D topological insulators, and it has been demonstrated that doping in appropriate levels can induce magnetism and even superconductivity in bulk Bi2Se3. In this article, we continue the examination of doping with sixth group transition elements, namely, Mo. The solubility of Mo in the host matrix is very low; however, it induces remarkable changes in the material properties. For low doping levels, Mo changes the intrinsic defect structure of Bi2Se3 featuring the Se vacancies toward a structure characterized by embedded Bi-2 double layers. Counterintuitively, Mo doping markedly enhances the mobility of free charge carriers in Bi2Se3 and drives its thermoelectric power factor to its maximum value over a broad temperature range. We provide evidence that the rather disordered structure must not be necessarily detrimental to charge transport in Bi2Se3.