Supporting Information Growth and Simultaneous Valleys Manipulation of Two-Dimensional MoSe2WSe2 Lateral Heterostructure Farman Ullah,† Yumin Sim,‡ Chinh Tam Le,† Maeng-Je Seong, ‡ Joon I. Jang,*,§ Sonny H. Rhim,† Bien Cuong Tran Khac,¶ Koo-Hyun Chung,¶ Kibog Park,∥Yangjin Lee,# Kwanpyo Kim,# Hu Young Jeong,& and Yong Soo Kim*,† †
Department of Physics and Energy Harvest Storage Research Center, University of Ulsan, Ulsan
44610, South Korea ‡
Department of Physics, Chung-Ang University, Seoul 06794, South Korea
§
Department of Physics, Sogang University, Seoul 04107, South Korea
¶
School of Mechanical Engineering, University of Ulsan, Ulsan 44610, South Korea
∥
Department of Physics and School of Electrical and Computer Engineering, Ulsan National
Institute of Science and Technology(UNIST), Ulsan 44919, South Korea #
Department of Physics, Ulsan National Institute of Science and Technology(UNIST), Ulsan
44919, South Korea &
UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and
Technology (UNIST), Ulsan 44919, South Korea
* E-mail:
[email protected] (J. I. Jang) and
[email protected] (Y. S. Kim)
S1 OM images of lateral and vertical heterostructures
Figure S1. OM images of in-plane MoSe2–WSe2 lateral and vertical heterostructures grown by the pulsed-laser-deposition-assisted method. (a) Isolated flakes, (b) continuous film-like lateral HSs, and (c-d) irregular vertical HSs locally formed over the lateral HS flakes.
S2 Experimental setup for polarization-sensitive PL measurements The 633nm line from a He-Ne laser was used as an excitation source for the polarizationresolved photoluminescence (PL) measurements. The right (left) circularly polarized light, marked as σ+ (σ-) was focused onto the sample, using a ×50 objective lens , located in a cryostat, held at temperatures below 50K. The laser beam area on the sample was ~1µm2. Either σ+ or σpolarized PL was selected and measured using a single-grating spectrometer with a focal length
of 50 cm coupled to a liquid-nitrogen-cooled charge-couple device (CCD) detector. The linearly polarized incident light was reflected by a beam splitter and then passed through a quarter-wave plate, resulting in the circularly polarized light σ+ (σ-), as shown in Fig. S2. The PL signal went through the same quarter-wave plate. Either σ+ or σ- polarized PL was selected by setting the linear polarizer #2 to either vertical or horizontal direction, respectively. In order to make sure that the linearly polarized light entering the spectrometer is the same polarization direction for both σ+ and σ- polarized PL, we changed the half-wave plate setting appropriately; this is required because the efficiency of the detection system itself has some polarization dependence.
Figure S2. Schematic illustration of the experimental setup for polarization-resolved PL measurements
S3 Room-temperature valley polarization
Figure S3. Polarization-sensitive PL measurements on pristine MoSe2, WSe2 and the interface MoSe2-WSe2 regions of the lateral HS at room temperature, signifying no essential valley polarization.