Theoretical Insight into Hydrogen-Assisted Chemical Vapor Deposition of MoTe₂

While chemical vapor deposition (CVD) has been widely used for synthesizing MoTe 2, a deep understanding of the molecular mechanism is still lacking. Here, we investigate the tellurization processes from gas-phase Mo 3 O 9 to MoTe 2 monolayer, without or with a H 2 atmosphere. Without H 2, both high barriers and high reaction energies hinder the growth of MoTe 2 . The introduction of H 2 facilitates the ring opening and chain breaking of Mo 3 O 9 and generates various intermediates involved in different possible reaction paths, which leads to reduced reaction energies and barriers for the tellurization of Mo-containing species. While the formation of a hydroxyl group results in the weakening of Mo–O bonds, the flexible Te coordination chemistry could easily adjust to form stable MoO x Te y H z intermediates. The fully tellurized MoTe 6 can easily nucleate at zigzag edge or kink sites of either 1T′- or 2H-MoTe 2, with low barriers. This study provides a molecular-level understanding of the MoTe 2 CVD growth.