Fig. 1: The variation of IX properties with different layer number of InSe.
From: Observation of giant dipole moments of interlayer excitons via layer engineering
a A schematic illustration of a representative device applied in this work. The device consists of 2L WS2 assembled with 4L and 5L InSe, with top (graphene) and bottom (gold) gate electrodes. b Schematic band structure of the WS2/InSe HS. Blue (Red) rectangles represent the band structures of the sole InSe (WS2) layer. Blue (red) arrows indicate intralayer transitions in InSe (WS2) layer. XA: A exciton in 2L-WS2. XI: indirect transition in 2L-WS2. The interlayer transition occurs between the valence band (providing holes) of WS2 and the conduction band (providing electrons) of InSe at \(\Gamma\) point. c Measured PL spectra of the 2L/4L HSs (dark purple) and 2L/5L HSs (light purple) at 77 K. Inset: microscopic image of the WS2/InSe HS encapsulated with top and bottom h-BN. The HS is on a gold film (50 nm) serving as the bottom gate, with a graphene layer serving as the top gate. Individual 2D flakes are outlined for clarity: WS2 (black dashed area), 4L InSe (blue dashed area), 5L InSe (green dashed area). Blue and red arrows indicate the corresponding peaks by pristine WS2 and InSe layer. The scale bar is 10 μm. d Evolution of PL emission spectra of IX for the 2L/4L HS with the increasing field. e Same as (d) but for the 2L/5L HS. f Electric-field dependence of the PL peak positions of IXs extracted from (d, e).
