A Facile Approach for Site-Selective and Large-Area Growth of Mos2 Through Heterogeneous Nucleation

Heterogeneous nucleation could be an effective approach to producing an array of transition metal dichalcogenides (TMDs) at controlled locations on a substrate. In this study, we prepared Pt mesa structures on the substrate to induce heterogeneous nucleation of MoS2 during chemical vapor deposition (CVD) and investigated the adsorption of nuclei using Monte Carlo (MC) simulations. The MC simulations suggest that the site-selectivity of MoS2 dramatically drops when the CVD growth time goes beyond the critical time at which nuclei fully cover the Pt mesas, and such critical time can be delayed when the size of Pt mesas increases. Our experimental observations on a clean array of MoS2 successfully synthesized on 10 um-width square Pt mesas but not on 4 um-width square Pt mesas support the MC simulation. We further designed a simple method employing dummy substrates to increase the yield of the site-selective MoS2 array. Computational fluid dynamics (CFD) simulation reveals that such dummy substrates restrict the precursor concentration and provide a confined channel for the precursors to react slowly, which benefits producing large-area and site-selective MoS2. Compared with conventional CVD, the total coverage of site-selective MoS2 has enlarged by seven times using dummy substrates.