Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3-xSe2

Alexander J.E. Rettie, Mihai Sturza, Christos D. Malliakas, Antia S. Botana, Duck Young Chung, Mercouri G. Kanatzidis

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

The two-dimensional material KCu3-xSe2 was synthesized using both a K2Se3 flux and directly from the elements. It crystallizes in the CsAg3S2 structure (monoclinic space group C2/m with a = 15.417(3) Å, b = 4.0742(8) Å, c = 8.3190(17) Å, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu3-xSe2]- layers separated by K+ ions. Thermal analysis indicated that KCu3-xSe2 melts congruently at ∼755 °C. UV-vis spectroscopy showed an optical band gap of ∼1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurements on single crystals yielded an in-plane resistivity of ∼6 × 10-1 ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K-1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm2 V-1 s-1) holes caused by relatively flat valence bands with substantial Cu 3d character and a significant concentration of Cu ion vacancy defects (p ∼ 1019 cm-3) in this material. Electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.

Original languageEnglish (US)
Pages (from-to)6114-6121
Number of pages8
JournalChemistry of Materials
Volume29
Issue number14
DOIs
StatePublished - Jul 25 2017
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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    Rettie, A. J. E., Sturza, M., Malliakas, C. D., Botana, A. S., Chung, D. Y., & Kanatzidis, M. G. (2017). Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3-xSe2. Chemistry of Materials, 29(14), 6114-6121. https://doi.org/10.1021/acs.chemmater.7b02117