Thermoelectric properties of Tl‐doped Bi 2 Se 3 single crystals

Applied Physics Letters

Schwingenschlögl

2014

We explain recent experimental findings on Tl-doped Bi2Se3 by determining the electronic and transport properties by first-principles calculations and semi-classical Boltzmann theory. Though Tl-doping introduces a momentum-dependent spin-orbit splitting, the effective mass of the carriers is essentially not modified, while the band gap is reduced. Tl is found to be exceptional in this respect as other dopants modify the dispersion, which compromises thermoelectricity. Moreover, we demonstrate that only after Tl-doping strain becomes an efficient tool for enhancing the thermoelectric performance. A high figure of merit of 0.86 is obtained for strong p-doping (7 × 1020 cm−3, maximal power factor) at 500 K under 2% tensile strain.

Section: à3supporting

confidence: 71%

Section: -5contrasting

confidence: 58%

Section: -5mentioning

confidence: 99%

Section: à3mentioning

confidence: 99%

See 2 more Smart Citations

Enhanced thermoelectric figure of merit in strained Tl-doped Bi2Se3

Saeed

Applied Physics Letters

Schwingenschlögl

2014

“…Bi 2 Se 3 ordinarily forms n-type specimens, so that more literature on n-type is available. Typical n-type mobilities at or even somewhat above these concentrations [35][36][37][38][39][40][41] are in this range or higher, so that assuming no great asymmetry in n-type vs p-type scattering rates, the assumed p-type mobilities are reasonable. The assumed carrier concentration dependence implies that mobility increases significantly as carrier concentration decreases, which is generally true until one reaches a limiting value, as in Ref.…”

Section: Calculation Of Optimal Doping Ranges and Potential Perfomentioning

confidence: 96%

Potential Thermoelectric Performance from Optimization of Hole-DopedBi2Se3

Parker

2011

Phys. Rev. X

We present an analysis of the potential thermoelectric performance of hole-doped Bi 2 Se 3 , which is commonly considered to show inferior room temperature performance when compared to (2008).]) the material may show optimized ZT values of unity or more in the 300-500 K temperature range and thus be suitable for cooling and moderate temperature waste heat recovery and thermoelectric solar cell applications. Central to this conclusion are the larger band gap and the relatively heavier valence bands of Bi 2 Se 3 .

Giant Rashba spin splitting in Bi₂ Se₃ :Tl

Phys. Status Solidi RRL

Saeed

Schwingenschlögl

2014

First‐principles calculations are employed to demonstrate a giant Rashba spin splitting in Bi2Se3:Tl. Biaxial tensile and compressive strain is used to tune the splitting by modifying the potential gradient. The band gap is found to increase under compression and decreases under tension, whereas the dependence of the Rashba spin splitting on the strain is the opposite. Large values of αR = 1.57 eV Å at the bottom of the conduction band (electrons) and αR = 3.34 eV Å at the top of the valence band (holes) are obtained without strain. These values can be further enhanced to αR = 1.83 eV Å and αR = 3.64 eV Å, respectively, by 2% tensile strain. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)