We report a reinvestigation of superconducting Sn1-xInxTe at both low and high In doping levels. Considering the system over a broad composition range in a single study allows us to characterize a significant change in the properties as a function of x: The system evolves from a weakly coupled p-type superconductor to a strongly coupled n-type superconductor with increasing indium content. Hall effect measurements show that the carrier density does not vary monotonically with indium content; a change from p-type to n-type is observed near 10% In doping. This is contrary to expectations dictating that In should be a p-type dopant in semiconducting SnTe, because it has one less valance electron than Sn. A crystallographic search for point defects at high x indicates that the material remains ideal NaCl-type over a wide composition range. Density functional theory calculations for In-doped SnTe support a picture where In does not act as a trivial hole dopant but instead forms a distinct, partly filled In 5s-Te5p hybridized state centered around EF, which is very different from what is seen for other nominal hole dopants such as Na, Ag, and vacant Sn sites.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics