Supplementary Information for“Continuous Heteroepitaxy of Two-Dimensional
Heterostructures Based on Layered Chalcogenides”
Yu Kobayashi1 , Shoji Yoshida2 , Mina Maruyama2 , Hiroyuki Mogi2 , Kota Murase2 ,Yutaka Maniwa1 , Osamu Takeuchi2 , Susumu Okada2 , Hidemi Shigekawa2 , Yasumitsu Miyata1,*1

Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

2

Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan

Table S1. Growth parameters for WS2 , WSe2 , MoS2 and MoSe2 monolayers in the present study.

WS2
WSe2
MoS2
MoSe2

Flow rate for bubbling of

Flow rate for bubbling

Flow rates

Furnacetransition metal precursorsof chalcogen precursorsof N2 /H2temperature(t-BuN=)2 W(NMe2 )2 ,(t-C4 H9 )2 S2 ,524/6

640 ºC

50 sccm

20 sccm

sccm(t-BuN=)2 W(NMe2 )2 ,(C2 H5 )2 Se2 ,524/6

50 sccm

20 sccm

sccm(t-BuN=)2 Mo(NMe2 )2 ,(t-C4 H9 )2 S2 ,444/6

100 sccm

50 sccm

sccm(t-BuN=)2 Mo(NMe2 )2 ,(C2 H5 )2 Se2 ,494/650 sccm

50 sccmsccm

640 ºC590 ºC
640 ºC

Figure S1. Optical microscopy images of WS2 grown on SiO2 /Si via MOCVD (a) with and (b) without NaCl.

Figure S2. Optical microscopy images of MoSe 2 grown with different supply rates for the metal andchalcogen precursors. The N2 bubbling rates through the Mo and Se precursors were (a) 50 and 50 sccm and(b) 50 and 200 sccm, respectively, and the combined N2 and H2 flow rate was 600 sccm.

Figure S3. (a 1 ) Optical image, (a 2 and a3 ) PL intensity maps (1.94 to 2.07 eV and 1.77 to 1.94 eV) and (a4 )Raman spectra of a MoS2 /WS2 heterostructure. (b1 ) Optical image, (b2 and b3 ) PL intensity maps (1.94 to 2.07
eV and 1.55 to 1.77 eV) and (b4 ) Raman spectra of a WSe2 /WS2 heterostructure. (c 1 ) Optical image, (c 2 and c3 )PL intensity maps (1.77 to 1.94 eV and 1.46 to 1.65 eV) and (c4 ) Raman spectra of a MoS2 /MoSe2
heterostructure. (d1 ) Optical image, (d2 and d3 ) PL intensity maps (1.55 to 1.77 eV and 1.46 to 1.65 eV) and(d4 ) Raman spectra of a WSe2 /MoSe2 heterostructure. (e 1 ) Optical image, (e 2 and e3 ) PL intensity maps (1.94to 2.07 eV and 1.46 to 1.65 eV) and (e4 ) Raman spectra of a WS2 /MoSe2 heterostructure. (f1 ) Optical image,(f2 and f3) PL intensity maps (1.77 to 1.94 eV and 1.55 to 1.77 eV) and (f4 ) Raman spectra of a MoS2 /WSe2
heterostructure. In the PL intensity maps, red, yellow, cyan and green correspond to the intensities of the MoS 2 ,MoSe2 , WS2 and WSe2 PL peaks, respectively.

Figure S4

STM images of the MoS2 /WS2 heterointerface from different regions. (Vs = + 1.2 V, (a) It = 0.2nA, (b) 0.06 nA, and (c) 0.25 nA, (d) Vs = + 1.3 V, and It = 0.1 nA)

Figure S5. (a) STM image (Vs = + 2.2 V, It = 10 pA), (b) color scale map of the dI/dV spectra acquired in thevicinity of the heterointerface. (c) Averaged dI/dV spectra obtained from the MoS2 and MoSe2 regions. In (a),the presence of bright spots in MoS2 (dark spots in MoSe2 ) is derived from the changes of local density ofstate by chalcogen substitution.

Figure S6. (a) Averaged dI/dV spectra obtained from the MoS2 , WS2 and heterointerface regions. (b) Color
scale map of the dI/dV spectra acquired in the vicinity of the heterointerface. (c) Calculated LDOS and (d)associated color scale map for the MoS2 /WS2 heterostructure. In (b) and (d), the red and black dotted lines
indicate the position of MoS2 /WS2 heterointerface.

Figure S7. (a) STM image of the area around the MoS2 /WS2 heterointerface (Vs = −2.5 V, It = 0.1 nA). (b) AdI/dV map acquired at a sample bias voltage of Vs = −2.19 V over the same area as in (a) (Vs = −2.5 V, It = 0.1nA). It is noted that the inhomogeneous dots of the dI/dV signal are derived from measurement noise.

Figure S8. PL spectra of the WS2 /MoS2 interfaces at different locations (a) within the identical grain and (b) indifferent triangle-shaped grains. Sharp peaks indicated by asterisks correspond to the Raman modes of thegraphite substrate. (c) Plot of PL peak positions of MoS2 and WS2 at the interface within the same grain (bluediamonds) and in different triangle-shaped grains (red circles).

Figure S9. Unit cell of a superlattice consisting of WS2 and MoS2 strips with widths of 10 zigzag MoS2 andWS2 chains