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Intrinsic topological insulator Bi(1.5)Sb(0.5)Te(3-x)Se(x) thin crystals.

Wang W, Li L, Zou W, He L, Song F, Zhang R, Wu X, Zhang F - Sci Rep (2015)

Bottom Line: A correlation between the structure and the physical properties has been revealed.We found out that within the rhombohedral structure, the composition with most Te substituting Se has the highest resistivity.On the other hand, segregation of other composition phases will introduce much higher bulk concentration.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures, Center of Photovoltaic Engineering and School of Physics, Nanjing University, Nanjing 210093, China.

ABSTRACT
The quaternary topological insulator (Bi,Sb)2(Te,Se)3 has demonstrated topological surface states with an insulating bulk. Scientists have identified an optimized composition of Bi(1.5)Sb(0.5)Te(1.7)Se(1.3) with the highest resistivity reported. But the physics that drive to this composition remains unclear. Here we report the crystal structure and the magneto-transport properties of Bi(1.5)Sb(0.5)Te(3-x)Se(x) (BSTS) series. A correlation between the structure and the physical properties has been revealed. We found out that within the rhombohedral structure, the composition with most Te substituting Se has the highest resistivity. On the other hand, segregation of other composition phases will introduce much higher bulk concentration.

No MeSH data available.


Related in: MedlinePlus

(a), (b) and (c) 2D carrier density (n2D), mobility (μ) and conductivity (G) of three conducting channels: Surface, Impurity band and Bulk.The solid purple line represents the Fermi-Dirac distribution of the bulk carrier density equivalent to 2D. The dashed red line represents the power law dependence of μ ∝ T−1, which suggests the mechanism of phonon scattering in these temperatures.
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f4: (a), (b) and (c) 2D carrier density (n2D), mobility (μ) and conductivity (G) of three conducting channels: Surface, Impurity band and Bulk.The solid purple line represents the Fermi-Dirac distribution of the bulk carrier density equivalent to 2D. The dashed red line represents the power law dependence of μ ∝ T−1, which suggests the mechanism of phonon scattering in these temperatures.

Mentions: The temperature dependent analysis results are plotted in Figure 4. As we discussed before, at high temperature, the dominated carrier are holes in the bulk valence band. When temperature decreases from the room temperature, the bulk carrier densities (blue squares in Figure 4a) decrease exponentially as carriers are frozen from the impurity band. Their temperature dependent density can be described as a classic Fermi-Dirac distribution of (solid purple line in Figure 4a), where n0 is the bulk carrier density of 5.3 × 1014 cm−2, and Ea of 18 meV is the energy gap between the impurity band and the top of the bulk valence band. This activation energy is very close to our previous estimation of 17 meV using Arrhenius plot (Figure 2b), assuring the consistency of our analysis. On the other hand, the carrier density of the impurity band (green triangles) and surface states (red circles) remain approximately constants of 1.3 × 1013 cm−2 and 1.2 × 1011 cm−2, respectively.


Intrinsic topological insulator Bi(1.5)Sb(0.5)Te(3-x)Se(x) thin crystals.

Wang W, Li L, Zou W, He L, Song F, Zhang R, Wu X, Zhang F - Sci Rep (2015)

(a), (b) and (c) 2D carrier density (n2D), mobility (μ) and conductivity (G) of three conducting channels: Surface, Impurity band and Bulk.The solid purple line represents the Fermi-Dirac distribution of the bulk carrier density equivalent to 2D. The dashed red line represents the power law dependence of μ ∝ T−1, which suggests the mechanism of phonon scattering in these temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300459&req=5

f4: (a), (b) and (c) 2D carrier density (n2D), mobility (μ) and conductivity (G) of three conducting channels: Surface, Impurity band and Bulk.The solid purple line represents the Fermi-Dirac distribution of the bulk carrier density equivalent to 2D. The dashed red line represents the power law dependence of μ ∝ T−1, which suggests the mechanism of phonon scattering in these temperatures.
Mentions: The temperature dependent analysis results are plotted in Figure 4. As we discussed before, at high temperature, the dominated carrier are holes in the bulk valence band. When temperature decreases from the room temperature, the bulk carrier densities (blue squares in Figure 4a) decrease exponentially as carriers are frozen from the impurity band. Their temperature dependent density can be described as a classic Fermi-Dirac distribution of (solid purple line in Figure 4a), where n0 is the bulk carrier density of 5.3 × 1014 cm−2, and Ea of 18 meV is the energy gap between the impurity band and the top of the bulk valence band. This activation energy is very close to our previous estimation of 17 meV using Arrhenius plot (Figure 2b), assuring the consistency of our analysis. On the other hand, the carrier density of the impurity band (green triangles) and surface states (red circles) remain approximately constants of 1.3 × 1013 cm−2 and 1.2 × 1011 cm−2, respectively.

Bottom Line: A correlation between the structure and the physical properties has been revealed.We found out that within the rhombohedral structure, the composition with most Te substituting Se has the highest resistivity.On the other hand, segregation of other composition phases will introduce much higher bulk concentration.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures, Center of Photovoltaic Engineering and School of Physics, Nanjing University, Nanjing 210093, China.

ABSTRACT
The quaternary topological insulator (Bi,Sb)2(Te,Se)3 has demonstrated topological surface states with an insulating bulk. Scientists have identified an optimized composition of Bi(1.5)Sb(0.5)Te(1.7)Se(1.3) with the highest resistivity reported. But the physics that drive to this composition remains unclear. Here we report the crystal structure and the magneto-transport properties of Bi(1.5)Sb(0.5)Te(3-x)Se(x) (BSTS) series. A correlation between the structure and the physical properties has been revealed. We found out that within the rhombohedral structure, the composition with most Te substituting Se has the highest resistivity. On the other hand, segregation of other composition phases will introduce much higher bulk concentration.

No MeSH data available.


Related in: MedlinePlus