We develop a tractable theoretical model to investigate the thermoelectric (TE) transport properties of surface states in topological insulator thin films (TITFs) of Bi2Sea at room temperature. The hybridization b...We develop a tractable theoretical model to investigate the thermoelectric (TE) transport properties of surface states in topological insulator thin films (TITFs) of Bi2Sea at room temperature. The hybridization between top and bottom surface states in the TITF plays a significant role. With the increasing hybridization-induced surface gap, the electrical conductivity and electron thermal conductivity decrease while the Seebeck coefficient increases. This is due to the metal-semiconductor transition induced by the surface-state hybridization. Based on these TE transport coefficients, the TE figure-of-merit ZT is evaluated. It is shown that ZT can be greatly improved by the surface-state hybridization. Our theoretical results are pertinent to the exploration of the TE transport properties of surface states in TITFs and to the potential application of Bi2Sea-based TITFs as high-performance TE materials and devices.展开更多
High-quality Bi2Se3 microcrystals were grown by the physical vapor transport (PVT) method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well facete...High-quality Bi2Se3 microcrystals were grown by the physical vapor transport (PVT) method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well faceted and have dimensions up to -200 μm, The growth proceeds by the layer-by-layer mecha- nism with the formation of flat low-growth rate facets. The phase composition of the grown crystals was identified by the X-ray single crystal structure analysis in space group R3m, a = 4.1356(3), C= 28.634(5)A, Z=3 (R=0.0147). The most probable twin planes in the tetradymite structure were evaluated by the pseudo translational sublattice merhad.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11304316the Ministry of Science and Technology of China under Grant No 2011YQ130018the Department of Science and Technology of Yunnan Province,and the Chinese Academy of Sciences
文摘We develop a tractable theoretical model to investigate the thermoelectric (TE) transport properties of surface states in topological insulator thin films (TITFs) of Bi2Sea at room temperature. The hybridization between top and bottom surface states in the TITF plays a significant role. With the increasing hybridization-induced surface gap, the electrical conductivity and electron thermal conductivity decrease while the Seebeck coefficient increases. This is due to the metal-semiconductor transition induced by the surface-state hybridization. Based on these TE transport coefficients, the TE figure-of-merit ZT is evaluated. It is shown that ZT can be greatly improved by the surface-state hybridization. Our theoretical results are pertinent to the exploration of the TE transport properties of surface states in TITFs and to the potential application of Bi2Sea-based TITFs as high-performance TE materials and devices.
文摘High-quality Bi2Se3 microcrystals were grown by the physical vapor transport (PVT) method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well faceted and have dimensions up to -200 μm, The growth proceeds by the layer-by-layer mecha- nism with the formation of flat low-growth rate facets. The phase composition of the grown crystals was identified by the X-ray single crystal structure analysis in space group R3m, a = 4.1356(3), C= 28.634(5)A, Z=3 (R=0.0147). The most probable twin planes in the tetradymite structure were evaluated by the pseudo translational sublattice merhad.