Atomically thin heterostructures based on single-layer tungsten diselenide and graphene.
Heterogeneous engineering of two-dimensional layered materials, including metallic graphene and semiconducting transition metal dichalcogenides, presents an exciting opportunity to produce highly tunable electronic and optoelectronic systems. In order to engineer pristine layers and their interfaces, epitaxial growth of such heterostructures is required. We report the direct growth of crystalline, monolayer tungsten diselenide (WSe2) on epitaxial graphene (EG) grown from silicon carbide. Raman spectroscopy, photoluminescence, and scanning tunneling microscopy confirm high-quality WSe2 monolayers, whereas transmission electron microscopy shows an atomically sharp interface, and low energy electron diffraction confirms near perfect orientation between WSe2 and EG. Vertical transport measurements across the WSe2/EG heterostructure provides evidence that an additional barrier to carrier transport beyond the expected WSe2/EG band offset exists due to the interlayer gap, which is supported by theoretical local density of states (LDOS) calculations using self-consistent density functional theory (DFT) and nonequilibrium Green's function (NEGF).
Department of Materials Science and Engineering and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Yu-Chuan
YC
Lin
Chih-Yuan S
CY
Chang
Ram Krishna
RK
Ghosh
Jie
J
Li
Hui
H
Zhu
Rafik
R
Addou
Bogdan
B
Diaconescu
Taisuke
T
Ohta
Xin
X
Peng
Ning
N
Lu
Moon J
MJ
Kim
Jeremy T
JT
Robinson
Robert M
RM
Wallace
Theresa S
TS
Mayer
Suman
S
Datta
Lain-Jong
LJ
Li
Joshua A
JA
Robinson
D004553:Electric Conductivity; D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D008567:Membranes, Artificial; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D012643:Selenium / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry*
D008567:Membranes, Artificial; D017973:Tungsten Compounds; D006108:Graphite; D012643:Selenium
LEED/LEEM; conductive AFM; direct growth; electron tunneling; graphene; heterostructures; tungsten diselenide (WSe2)