Structural Changes in 2D BiSe Bilayers as n Increases in (BiSe)1+δ(NbSe2)n(n = 1-4) Heterostructures.
(BiSe)1+δ(NbSe2)nheterostructures with n = 1-4 were synthesized using modulated elemental reactants. The BiSe bilayer structure changed from a rectangular basal plane with n = 1 to a square basal plane for n = 2-4. The BiSe in-plane structure was also influenced by small changes in the structure of the precursor, without significantly changing the out-of-plane diffraction pattern or value of the misfit parameter, δ. Density functional theory calculations on isolated BiSe bilayers showed that its lattice is very flexible, which may explain its readiness to adjust shape and size depending on the environment. Correlated with the changes in the BiSe basal plane structure, analysis of scanning transmission electron microscope images revealed that the occurrence of antiphase boundaries, found throughout the n = 1 compound, is dramatically reduced for the n = 2-4 compounds. X-ray photoelectron spectroscopy measurements showed that the Bi 5d3/2, 5d5/2doublet peaks narrowed toward higher binding energies as n increased from 1 to 2, also consistent with a reduction in the number of antiphase boundaries. Temperature-dependent electrical resistivity and Hall coefficient measurements of nominally stoichiometric samples in conjunction with structural refinements and XPS data suggest a constant amount of interlayer charge transfer independent of n. Constant interlayer charge transfer is surprising given the changes in the BiSe in-plane structure. The structural flexibility of the BiSe layer may be useful in designing multiple constituent heterostructures as an interlayer between structurally dissimilar constituents.
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
Gavin
G
Mitchson
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
Erik
E
Hadland
Institut für Physik, Technische Universität Chemnitz , Reichenhainer Strasse 70, D-09126 Chemnitz, Germany.
Fabian
F
Göhler
Institut für Physik, Technische Universität Chemnitz , Reichenhainer Strasse 70, D-09126 Chemnitz, Germany.
Martina
M
Wanke
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
Marco
M
Esters
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
Jeffrey
J
Ditto
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
Erik
E
Bigwood
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
Kim
K
Ta
Department of Materials Science and Engineering, University of Florida , Gainesville, Florida 32611, United States.
Richard G
RG
Hennig
Institut für Physik, Technische Universität Chemnitz , Reichenhainer Strasse 70, D-09126 Chemnitz, Germany.
Thomas
T
Seyller
Department of Chemistry, University of Oregon , Eugene, Oregon 97401, United States.
David C
DC
Johnson
charge transfer; electronic environment; electronic transport; heterostructures; two-dimensional materials