期刊
PHYSICAL REVIEW B
卷 79, 期 19, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.79.195208
关键词
bismuth compounds; crystal defects; crystal growth; Fermi level; insulators; photoelectron spectra; scanning tunnelling microscopy; Seebeck effect; valence bands
资金
- AFOSR [FAA9550-06-1-0530]
- NSF MRSEC [DMR-0819860]
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [0819860, GRANTS:14060168] Funding Source: National Science Foundation
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 mu V/K at room temperature are reported. These crystals show an anomalous peak in the Seebeck coefficient at low temperatures, reaching +120 mu V 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.
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