p-type Bi2 Se3 for Topological Insulator and Low-Temperature Thermoelectric Applications
The growth and elementary properties of p-type Bi2Se3 single crystals are reported. Based on a hypothesis about the defect chemistry of Bi2Se3, 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 Bi1.98Ca0.02Se3 relative to the n-type material. p-type single crystals with ab-plane Seebeck coefficients of +180 μV/K at room temperature are reported. These crystals show an anomalous peak in the Seebeck coefficient at low temperatures, reaching +120 μV K-1 at 7 K, giving them a high thermoelectric power factor at low temperatures. In addition to its interesting thermoelectric properties, p-type Bi2Se3 is of substantial interest for studies of technologies and phenomena proposed for topological insulators.
Y. S. Hor et al., "p-type Bi2 Se3 for Topological Insulator and Low-Temperature Thermoelectric Applications," Physical review B: Condensed matter and materials physics, vol. 79, no. 19, American Physical Society (APS), May 2009.
The definitive version is available at https://doi.org/10.1103/PhysRevB.79.195208
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