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We study the nucleation mechanism and morphology evolution of MoS_2 flakes grown by chemical vapor deposition(CVD)on SiO_2/Si substrates with using S and MoO_3 powders.The MoS_2 flake is of monolayer with triangular nucleation,which might arise from the initial MoO_3-xthat is deposited on the substrate,and then bonded with S to form MoS_2 flake.The ratio of Mo and S is higher than 1:2 at the beginning with Mo terminated triangular nucleation formed.After that,the morphology of MoS_2 flake evolves from triangle to similar hexagon,then to truncated triangle which is determined by the faster growth speed of Mo termination than that of S termination under the S rich environment.The nucleation density does not increase linearly with the increase of reactant concentration,which could be explained by the two-dimensional nucleation theory.
We study the nucleation mechanism and morphology evolution of MoS_2 flakes grown by chemical vapor deposition (CVD) on SiO_2 / Si substrates with using S and MoO_3 powders. MoS_2 flake is of monolayer with triangular nucleation, which might arise from the initial MoO_3-xthat is deposited on the substrate, and then bonded with S to form MoS_2 flake. The ratio of Mo and S is higher than 1: 2 at the beginning with Molated triangular nucleation formed. After that, the morphology of MoS_2 flake evolves from triangle to similar hexagon, then to truncated triangle which is determined by the faster growth speed of Mo termination than that of S termination under the S rich environment does not increase linearly with the increase of reactant concentration, which could be explained by the two -dimensional nucleation theory.