Fig. 1: Moiré superlattice and interlayer exciton emission in a WSe2/WS2/WSe2 heterotrilayer.
a Schematic illustration of a vertically stacked WSe2/WS2/WSe2 twisted-angle heterotrilayer with hexagonal boron nitride (h-BN) on a SiO2/Si substrate. The twisted WSe2/WS2/WSe2 heterotrilayer is a system composed of two-layer WSe2 and one-layer WS2. The top and bottom sheets are aligned, and the middle sheet is rotated by a θ angle of approximately 3° relative to the other two sheets. b Schematic diagram of the alignment of type II bands in the WSe2/WS2/WSe2 heterotrilayer. The energy levels are represented by black solid lines, and the interlayer excitons and intralayer excitons are marked by dashed ellipses. c Optical microscopy image of the WSe2/WS2/WSe2 heterotrilayer, with the heterojunctions encapsulated with flakes of BN (Fig. S1). d Raman mapping of a twisted WSe2/WS2/WSe2 heterotrilayer. e The PL spectra of heterojunctions with different layers at room temperature. f Measured and fitted the SHG signals of the top WSe2 monolayer and middle WS2 monolayer regions of the sample, which confirm the 3° twist angle between the top and middle layers
