5 years ago

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

Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2
Duck Young Chung, Alexander J. E. Rettie, Mihai Sturza, Mercouri G. Kanatzidis, Christos D. Malliakas, Antia S. Botana
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.

Publisher URL: http://dx.doi.org/10.1021/acs.chemmater.7b02117

DOI: 10.1021/acs.chemmater.7b02117

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.