2019/08/27 by Jisoo Moon, Zengle Huang, Weida Wu +1
Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Chemical and Physical Properties of Materials #Coupling (piping) #Coupling strength #Dopant #Doping #Ion #Thin film #Topological Materials and Phenomena #Topological insulator #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevmaterials.4.024203
published as Phys. Rev. Materials 4, 024203 (2020)
arxiv created 2019/08/27 · openalex created_date 2019/09/05 · openalex publication_date 2020/02/10 · arxiv updated 2020/02/12 · openalex updated_date 2026/08/06
Due to the high density of native defects, the prototypical topological insulator (TI), Bi2Se3, is naturally n-type. Although Bi2Se3 can be converted into p-type by substituting 2+ ions for Bi, only light elements such as Ca have so far been effective as the compensation dopant. Considering that strong spin-orbit coupling (SOC) is essential for the topological surface states, a light element is undesirable as a dopant because it weakens the strength of SOC. In this sense, Pb, which is the heaviest 2+ ion, located right next to Bi in the Periodic Table, is the most ideal p-type dopant for Bi2Se3. However, Pb-doping has so far failed to achieve p-type Bi2Se3 not only in thin films but also in bulk crystals. Here, by utilizing an interface engineering scheme, we have achieved the first Pb-doped p-type Bi2Se3 thin films. Furthermore, at heavy Pb-doping, the mobility turns out to be substantially higher than that of Ca-doped samples, suggesting that Pb is a less disruptive dopant than Ca. The availability of Pb-doped p-type Bi2Se3 films will provide opportunities to study a Fermi-level tunable TI system while preserving the SOC strength.