Fig. 2: Single-layer WS2/WSe2 in-plane heterostructure sample prepared on a Si/SiO2 substrate.
a Optical microscope image of the sample setup, and a schematic illustration of the sample showing the structure of the area surrounded by the square frame in the optical image. After growing a threefold-symmetric WS2 structure, a WSe2 structure is grown around it18. In the schematic illustration, the Au electrode on WS2 is transparent. The pale-yellow areas above and below the Au electrodes are Au thin films of different thicknesses. The left and right sides of the SiO2/Si regions are shadows due to the Au thin films on the outside. b Schematic of the measurement setup. c, STM topography image acquired at the WSe2/WS2 heterointerface, which position is shown in a with a green square. d Line profiles along AB and CD in c. The ripple structure is clearly shown in the WS2 area. e Fluorescence spectrum measured in each region of WSe2 and WS2 (excitation wavelength 532 nm, spot diameter 2 μm, excitation power 2.5 mW). Measured positions are marked in a with a red (WSe2) and a blue (WS2) circles, respectively. The spectrum for WS2 (blue curve) can be divided into two peaks (pink and light blue curves) with different intensity by fitting.
