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

Abstract

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 Bi2Te3, 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 Bi2Te3. 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.

Studies on the origin of the interfacial superconductivity of Sb 2 Te 3 /Fe 1+y Te heterostructures

“…Reflection high-energy electron diffraction (RHEED) patterns were captured after the growth of Fe1+yTe and Sb2Te3 layers. Figure 1a The epitaxial growth of bismuth and antimony chalcogenides on substrates that have six-fold symmetry, such as Al2O3(0001) 22 , Si(111) 23 , BaF2(111) 24,25 InP(111) 26 and GaAs(111) 27 , usually results in two mirror-symmetric twin domains due to the fact that there are two stacking sequences (ABCAB and ACBAC) along the [0001] direction for one QL of these chalcogenides.…”

Visualizing the double-gyroid twin

“…TBs that form reentrant growth faces are important for accelerating crystal growth ( 5 ) and the presence of twins can strongly influence mechanical behavior ( 6 ). The unique character of the bonding in the TBs can also influence for example, electrical ( 7 ) and optical ( 8 ) properties. Twin structures can be constructed via the symmetry operations of reflection, rotation, or inversion ( 9 ).…”

Pulsed current-voltage electrodeposition of stoichiometric Bi2Te3 nanowires and their crystallographic characterization by transmission electron backscatter diffraction

“…This plane, (0 1 1 0), corresponds to the [210] direction of bismuth telluride which was measured by XRD, and the (300) plane, and thus confirms those measurements. However, "in other cases" the 70 nm nanowires also showed the 60°twin boundaries [36], which are presented below ( Figure 6). The length of the corresponding twins varied between 500 nm and 1.5 µm.…”

“…In the literature, some studies about bismuth telluride reported that the figure of merit was enhanced by the presence of twinning in films [36] and nanowires [37]. Kwang-Chon Kim and coworkers reported that 60°twin boundaries in bismuth telluride films increase the electrical conductivity by increasing the mobility of the electrons [36]. Moreover, Ho Sun Shin et al reported that the figure of merit is enhanced by the incorporation of twins into bismuth telluride nanowires because the structure changes the thermal conductivity and carrier concentration.…”