Free-electron creation at the 60° twin boundary in Bi2Te3

• Published in: Nature communications Vol. 7; no. 1; p. 12449
• Main Authors: Kim, Kwang-Chon, Lee, Joohwi, Kim, Byung Kyu, Choi, Won Young, Chang, Hye Jung, Won, Sung Ok, Kwon, Beomjin, Kim, Seong Keun, Hyun, Dow-Bin, Kim, Hyun Jae, Koo, Hyun Cheol, Choi, Jung-Hae, Kim, Dong-Ik, Kim, Jin-Sang, Baek, Seung-Hyub
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-08-2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119; 639/301/299; Electrons; Grain boundaries; Heat conductivity; Humanities and Social Sciences; Interfaces; multidisciplinary; Organic chemicals; Physical properties; Point defects; Science; Science (multidisciplinary); Symmetry; South Korea
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms12449

Interfaces, such as grain boundaries in a solid material, are excellent regions to explore novel properties that emerge as the result of local symmetry-breaking. For instance, at the interface of a layered-chalcogenide material, the potential reconfiguration of the atoms at the boundaries can lead to a significant modification of the electronic properties because of their complex atomic bonding structure. Here, we report the experimental observation of an electron source at 60° twin boundaries in Bi
2
Te
3
, a representative layered-chalcogenide material. First-principles calculations reveal that the modification of the interatomic distance at the 60° twin boundary to accommodate structural misfits can alter the electronic structure of Bi
2
Te
3
. The change in the electronic structure generates occupied states within the original bandgap in a favourable condition to create carriers and enlarges the density-of-states near the conduction band minimum. The present work provides insight into the various transport behaviours of thermoelectrics and topological insulators.
Grain boundaries in polycrystalline materials may offer the opportunity to explore physical phenomena that do not normally occur within the crystal grains. Here, the authors show that twin boundaries in Bi
2
Te
3
works as an electron supply for the whole bulk material.