Fig. 6: Momentum-resolved EEL spectra (q-EELS) show the exciton region of hBN and the WSe₂-hBN heterostructure at finite |q| .

Individual spectra are shown for q from |q| = 0.15 × |Γ − Γ^′| to |q| = 0.85 × |Γ − Γ^′| (of the hBN lattice) in the Γ → M direction for a hBN and b the WSe₂-hBN heterostructure. Individual spectra are shown for q from |q| = 0.05 × |Γ−Γ^′| to |q| = 0.85 × |Γ − Γ^′′| (of the hBN lattice) in the Γ → K direction for c hBN and d the WSe₂-hBN heterostructure. e Overlaid spectra for q = 0 and at K and M’ point of both, hBN and WSe₂-hBN heterostructure show the spectral shape redistribution for the excitonic peaks originating from hBN (denoted by ‘1’ and ‘2’). f The q-EEL spectra acquired at Γ (q = 0) for multi-layer WSe₂ (solid line for the structure used here and dashed line for a reference of multi-layer WSe₂ with an increased thickness) and WSe₂-hBN heterostructure (solid line for the structure used here and dashed line for a reference of WSe₂-hBN with an increased thickness) as well as a reference spectra for a monolayer WSe₂ show changes in the peak position and relative intensity of higher energy WSe₂ excitons, including in the B exciton region (grey shaded region) and C exciton region (yellow shaded regions). Only the A exciton peak (light red shaded region) exhibits a slight shift when compared to the reference monolayer WSe₂ (pink spectra). The spectra are offset vertically for clarity.