posted on 2021-08-06, 23:13authored byMarisa
A. Choffel, Renae N. Gannon, Fabian Göhler, Aaron M. Miller, Douglas L. Medlin, Thomas Seyller, David C. Johnson
The
synthesis and electrical properties of a new misfit compound
containing BiSe, Bi2Se3, and MoSe2 constituent layers are reported. The reaction pathway involves competition
between the formation of (BiSe)1+x(Bi2Se3)1+y(BiSe)1+x(MoSe2) and [(Bi2Se3)1+y]2(MoSe2).
Excess Bi and Se are required in the precursor to synthesize (BiSe)1+x(Bi2Se3)1+y(BiSe)1+x(MoSe2). High-angle annular dark field-scanning transmission electron microscopy
(HAADF-STEM) confirm the stacking sequence of the heterostructure.
Small grains of both 2H- and 1T-MoSe2 are observed in the
MoSe2 layers. X-ray photoelectron spectroscopy (XPS) indicates
that there is a significantly higher percentage of 1T-MoSe2 in (BiSe)1+x(Bi2Se3)1+y(BiSe)1+x(MoSe2) than in (BiSe)0.97(MoSe2), suggesting that more charge transfer to MoSe2 occurs
due to the additional BiSe layer. The additional charge transfer results
in (BiSe)1+x(Bi2Se3)1+y(BiSe)1+x(MoSe2) having a low resistivity (14–19 μΩ
m) with metallic temperature dependence. The heterogeneous mix of
MoSe2 polytypes observed in the XPS complicates the interpretation
of the Hall data as two bands contribute to the electrical continuity.