Figure 1. Atomic structures and electronic band structures.

(a–f) Atomic structures of the freestanding ML MoS₂ (a), ML MoS₂ on HfO₂ substrate (b), ML MoS₂ sandwiched by HfO₂ (c), ML MoS₂ on Au metallic substrate (d), ML MoS₂ sandwiched by Au (e), and ML MoS₂ sandwiched by Ag (f). The Mo, S, Hf, O, Au, and Ag atoms are indicated by the purple, yellow, gold, red, yellow, and blue color balls, respectively. (g–l) Calculated LDA band structures of the freestanding ML MoS₂ (g), ML MoS₂ on HfO₂ (h), ML MoS₂ sandwiched by HfO₂ (i), ML MoS₂ on Au (j), ML MoS₂ sandwiched by Au (k), and ML MoS₂ sandwiched by Ag (l). The blue filled dots (g–l) indicate the projected states to the ML MoS₂. (m–r) Calculated GW band structures of the freestanding ML MoS₂ (m), ML MoS₂ on HfO₂ (n), ML MoS₂ sandwiched by HfO₂ (o), ML MoS₂ on Au (p), ML MoS₂ sandwiched by Au (q), and ML MoS₂ sandwiched by Ag (r) are shown. The red filled dots (m–r) indicate the projected states to the ML MoS₂. The arrows (g–r) indicate the direct bandgap at the K valley of the ML MoS₂. The Fermi levels of the Au and Ag containing systems (j–l,p–r) are indicated by the green dashed lines.