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Title: Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu 3–xSe 2

Abstract

The two-dimensional material KCu 3–xSe 2 was synthesized using both a K 2Se 3 flux and directly from the elements. It crystallizes in the CsAg 3S 2 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 [Cu 3–xSe 2]– layers separated by K + ions. Thermal analysis indicated that KCu 3–xSe 2 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 cm 2 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 ~ 10 19 cm –3) in this material. In conclusion,more » electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.« less

Authors:
ORCiD logo [1];  [2];  [3];  [1];  [1]; ORCiD logo [3]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Northwestern Univ., Evanston, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); German Research Foundation (DFG)
OSTI Identifier:
1393193
Grant/Contract Number:  
AC02-06CH11357; STU 695/1-1
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 14; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Rettie, Alexander J. E., Sturza, Mihai, Malliakas, Christos D., Botana, Antia S., Chung, Duck Young, and Kanatzidis, Mercouri G. Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b02117.
Rettie, Alexander J. E., Sturza, Mihai, Malliakas, Christos D., Botana, Antia S., Chung, Duck Young, & Kanatzidis, Mercouri G. Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2. United States. doi:10.1021/acs.chemmater.7b02117.
Rettie, Alexander J. E., Sturza, Mihai, Malliakas, Christos D., Botana, Antia S., Chung, Duck Young, and Kanatzidis, Mercouri G. Wed . "Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2". United States. doi:10.1021/acs.chemmater.7b02117. https://www.osti.gov/servlets/purl/1393193.
@article{osti_1393193,
title = {Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2},
author = {Rettie, Alexander J. E. and Sturza, Mihai and Malliakas, Christos D. and Botana, Antia S. and Chung, Duck Young and Kanatzidis, Mercouri G.},
abstractNote = {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. In conclusion, electronic band structure calculations showed that electrons should be significantly more mobile in this structure type.},
doi = {10.1021/acs.chemmater.7b02117},
journal = {Chemistry of Materials},
number = 14,
volume = 29,
place = {United States},
year = {Wed Jun 21 00:00:00 EDT 2017},
month = {Wed Jun 21 00:00:00 EDT 2017}
}

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