p -type Bi 2 Se 3 for topological insulator and low-temperature thermoelectric applications

By Y. Hor, Anthony Richardella, P. Roushan, Yuqi Xia, J. Checkelsky, A. Yazdani, M. Z. Hasan, N. Ong, R. Cava. 2009

536 citations recorded by the source corpus.

The growth and elementary properties of $p$-type ${\text{Bi}}_{2}{\text{Se}}_{3}$ single crystals are reported. Based on a hypothesis about the defect chemistry of ${\text{Bi}}_{2}{\text{Se}}_{3}$, the $p$-type behavior has been induced through low-level substitutions (1% or less) of Ca for Bi. Scanning tunneling microscopy is employed to image the defects and establish their charge. Tunneling and angle-resolved photoemission spectra show that the Fermi level has been lowered into the valence band by about 400 meV in ${\text{Bi}}_{1.98}{\text{Ca}}_{0.02}{\text{Se}}_{3}$ relative to the $n$-type material. $p$-type single crystals with $ab$-plane Seebeck coefficients of $+180\text{ }\ensuremath{\mu}\text{V}/\text{K}$ at room temperature are reported. These crystals show an anomalous peak in the Seebeck coefficient at low temperatures, reaching $+120\text{ }\ensuremath{\mu}\text{V}\text{ }{\text{K}}^{\ensuremath{-}1}$ at 7 K, giving them a high thermoelectric power factor at low temperatures. In addition to its interesting thermoelectric properties, $p$-type ${\text{Bi}}_{2}{\text{Se}}_{3}$ is of substantial interest for studies of technologies and phenomena proposed for topological insulators.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/32774756d27a09e113461858dea0506bb44abd0d

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In Atomic and Molecular Physics, and Optics

1. M. Zahid Hasan
2. Su-Yang Xu
3. Hsin Lin
4. Arun Bansil
5. Tanmoy Das
6. R. Cava
7. Y. Hor
8. N. Ong

In Materials Chemistry

1. M. Zahid Hasan
2. Su-Yang Xu
3. Hsin Lin
4. Arun Bansil
5. R. Cava
6. Tanmoy Das
7. N. Ong
8. Y. Hor

Citations in the corpus

• First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime (2010, methodology): “To lower the EF of Bi2Se3 into the bulk band gap, we substituted trace amounts of Ca for Bi in as-grown Bi2Se3, where Ca has been shown to act as a hole donor by scanning tunnelling microscopy and thermoelectric transport studies [16].”
• A topological insulator surface under strong Coulomb, magnetic and disorder perturbations (2011, background): “The Fermi level of grown crystals is usually found to be located in the bulk conduction band due to selenium vacancy defects, however it was subsequently shown that with Ca doping or NO2 surface deposition, the Fermi level can be placed at the Dirac point reaching the topological transport regime [7”