Compositional control of topological surface transport in In-doped SnTe thin films grown by sputtering

Topological crystalline insulators such as SnTe are promising for electronic and spintronic applications owing to their robust topological surface states; however, their practical utilization requires scalable fabrication methods and precise control of carrier transport. In this study, we investigated In-doped SnTe thin films fabricated by RF magnetron sputtering, a method compatible with industrial applications, to clarify the compositional regime in which weak anti-localization, consistent with topological surface transport, is observed. The stoichiometric non-doped SnTe films exhibited similar temperature dependences of channel weight and phase coherence length over a wide thickness range from 8 to 212 nm. Moreover, by varying the In concentration and cation–anion balance, we analyzed the relationships among composition, defect-related scattering, and phase-breaking processes in the coherent transport channels. Near-stoichiometric compositions are associated with reduced defect scattering, while In-doping is consistent with partial compensation of Sn vacancies, leading to a decrease in carrier density and a change in the dominant scattering mechanism. These results indicate that two-dimensional transport can be promoted in sputtered SnTe films. This study provides compositional considerations and a transport-based approach for examining SnTe-based topological materials.