Extended Data Fig. 1: Device information.
From: Correlated interlayer exciton insulator in heterostructures of monolayer WSe2 and moiré WS2/WSe2
a–c, Three side-view schematics, optical microscope images, and second harmonic generation (SHG) results of Device I (a), Device II (b), and Device III (c). a, The top (bottom) hBN thickness is approximately 50 nm (50 nm). The stack is capped with an approximately 65 nm thick hBN layer. In the optical microscopy image, the dashed green (red) line outlines the WS2 (WSe2) layer in the moiré heterostructure, the dashed yellow line outlines the WSe2 monolayer, the dashed black (white) line outlines the top (bottom) FLG gate. These three flakes are aligned, as demonstrated by the SHG signal. The moiré bilayer has a near-60º twist angle. b, The top (bottom) hBN thickness is approximately 80 nm (40 nm). The stack is capped with an approximately 55 nm thick hBN layer. In the optical microscopy image, the dashed green (red) line outlines the WS2 (WSe2) layer in the moiré heterostructure, the dashed yellow line outlines the monolayer WSe2, and the dashed black line outlines the top and bottom FLG gate. The solid lines correspond to a few-layer TMDCs that are attached to the monolayers. The twist angle between the moiré bilayer and the WSe2 monolayer is around 25 degrees. The moiré bilayer has a near-zero twist angle as it shows an enhanced SHG signal. c, The stacking order of Device III is opposite to that in Device I and Device II. The moiré bilayer in device III is below the WSe2 monolayer. The top (bottom) hBN thickness is approximately 9 nm (15 nm). The stack is further capped with an approximately 8 nm thick hBN layer. In the optical microscopy image, the dashed green (red) line outlines the WS2 (WSe2) layer in the moiré heterostructure, the dashed yellow line outlines the monolayer WSe2, the dashed black (white) line outlines the top (bottom) FLG gate. The solid lines correspond to a few-layer TMDCs that are attached to the monolayers. These three layers are aligned, as determined by the SHG measurements. The moiré bilayer in device III has a near-zero twist angle.
