Figure 3
From: Model dielectric function for 2D semiconductors including substrate screening
Excitonic optical response of MoS2 (a) and monolayer hBN (b) deposited on the various substrates indicated on the figures. κa (in-plane) values are from ref. 4 (MoS2, hBN), ref. 29 (Si, GaAs, AlP), ref. 30 (GaN) and ref. 31 (SiO2). On the figure, we also indicate the average valence charge densities na used to model the q-dependence of the substrate dielectric function in Eq. 1. Note, the energy axis is displaced by the exciton binding energy. Hence, the locations of the band gaps on the displaced energy axis correspond to exciton binding energies, and are indicated by the triangles. To resolve the exciton fine-structure, the k-point sampling is increased to 200 × 200 for hBN and 150 × 150 for MoS2. Additionally, the phenomenological broadening is reduced to 10 meV. Note, the results for hBN are displayed using a logarithmic y-axis due to the dominating main absorption peak, and the y-limits of all figures are identical to the results for vacuum.
