Fig. 3: Tip-enhanced spectroscopy of the MoSe₂-WSe₂ interface.

a Schematic of the TEPL, TERS experimental set-up. b Spectrally integrated TEPL intensity colormap of the interface area. The red (respectively blue) color intensity is the value of integrated PL from 1.620 eV to 1.650 eV (respectively from 1.550 eV to 1.580 eV). c Typical TEPL spectra taken along the dashed line in b. Zone (1) on the left: 500 nm from the interface inside the MoSe₂ area (x = −0.5 μm). Zone (2) at the center: 100 nm from the interface inside the WSe₂ area (x = 0.1 μm). Zone (3) on the right: 500 nm from the interface inside the WSe₂ area (x = 0.5 μm). Three different excitonic components are observed in these curves: the WSe₂ neutral exciton(A\({}_{1s}^{WS{e}_{2}}\)), the dark (out-of-plane) exciton (X\({}_{WS{e}_{2}}^{D}\)), and the MoSe₂ neutral exciton (A\({}_{1s}^{MoS{e}_{2}}\)) and their respective contributions are used to fit the experimental data using individual Lorentzian function: red, black and light blue dashed lines respectively. d A\(^{\prime}\)1(Γ) phonon wavenumber measured by TERS along the dashed line in b as a function of the tip position. e Energy of the individual Lorentzian peaks obtained from the fitting procedure displayed in c. f Amplitude of the individual Lorentzian peaks obtained from the fitting procedure displayed in c. In figure d, e, f the position of the interface appears as a vertical black dashed line. The positions where the PL spectra of c were taken appear as light vertical grey dashed lines.