TY - JOUR
T1 - Low-Frequency Raman Fingerprints of Two-Dimensional Metal Dichalcogenide Layer Stacking Configurations
AU - Puretzky, Alexander A.
AU - Liang, Liangbo
AU - Li, Xufan
AU - Xiao, Kai
AU - Wang, Kai
AU - Mahjouri-Samani, Masoud
AU - Basile, Leonardo
AU - Idrobo, Juan Carlos
AU - Sumpter, Bobby G.
AU - Meunier, Vincent
AU - Geohegan, David B.
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/6/23
Y1 - 2015/6/23
N2 - The tunable optoelectronic properties of stacked two-dimensional (2D) crystal monolayers are determined by their stacking orientation, order, and atomic registry. Atomic-resolution Z-contrast scanning transmission electron microscopy (AR-Z-STEM) and electron energy loss spectroscopy (EELS) can be used to determine the exact atomic registration between different layers, in few-layer 2D stacks; however, fast optical characterization techniques are essential for rapid development of the field. Here, using two- and three-layer MoSe2 and WSe2 crystals synthesized by chemical vapor deposition, we show that the generally unexplored low frequency (LF) Raman modes (<50 cm-1) that originate from interlayer vibrations can serve as fingerprints to characterize not only the number of layers, but also their stacking configurations. Ab initio calculations and group theory analysis corroborate the experimental assignments determined by AR-Z-STEM and show that the calculated LF mode fingerprints are related to the 2D crystal symmetries.
AB - The tunable optoelectronic properties of stacked two-dimensional (2D) crystal monolayers are determined by their stacking orientation, order, and atomic registry. Atomic-resolution Z-contrast scanning transmission electron microscopy (AR-Z-STEM) and electron energy loss spectroscopy (EELS) can be used to determine the exact atomic registration between different layers, in few-layer 2D stacks; however, fast optical characterization techniques are essential for rapid development of the field. Here, using two- and three-layer MoSe2 and WSe2 crystals synthesized by chemical vapor deposition, we show that the generally unexplored low frequency (LF) Raman modes (<50 cm-1) that originate from interlayer vibrations can serve as fingerprints to characterize not only the number of layers, but also their stacking configurations. Ab initio calculations and group theory analysis corroborate the experimental assignments determined by AR-Z-STEM and show that the calculated LF mode fingerprints are related to the 2D crystal symmetries.
KW - first-principles calculations
KW - low-frequency Raman spectroscopy
KW - stacking configurations
KW - transition metal dichalcogenides
KW - two-dimensional materials
UR - http://www.scopus.com/inward/record.url?scp=84934892656&partnerID=8YFLogxK
U2 - 10.1021/acsnano.5b01884
DO - 10.1021/acsnano.5b01884
M3 - Article
AN - SCOPUS:84934892656
SN - 1936-0851
VL - 9
SP - 6333
EP - 6342
JO - ACS Nano
JF - ACS Nano
IS - 6
ER -