Influence of the gold substrate on the electronic properties of MoS₂: an ab initio study

Apart from its low cost, 2D MoS₂ exhibits strong chemical stability, high specific capacitance, and a direct band gap, making it an ideal candidate in many optoelectronic applications. Its electronic properties can be tuned by the number of atomic layers, strain, an electric field, or the underlying substrate. Here, we analyze the impact of a gold substrate on the electronic properties of monolayer MoS₂. Employing the full-potential all-electron code exciting, we perform ab initio calculations based on density-functional theory (DFT) and the G₀W₀ approximation of many-body perturbation theory. In particular, we investigate the renormalization of the band gap and band structure due to the image-charge effect. We explore the impact of this dynamical correlation effect as a function of substrate thickness and the relative positioning of the two materials at the interface. At the DFT level, the direct band gap at the K point remains unchanged at 1.44 eV regardless of the presence of the substrate. However, with G₀W₀ the band gap decreases from 2.43 eV to 1.91 eV agreeing very well to reported measurements. Furthermore, with our G₀W₀ results, we also predict the band gap renormalizations for other substrates.