Growth mechanism for vertically oriented layered In2Se3 nanoplates

Vertically oriented layered $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ nanoplates have been grown by chemical vapor deposition. It is demonstrated that the growth is subject to the species of substrates because the morphologies of nanoplates grown on mica and $\mathrm{Si}{\mathrm{O}}₂/\mathrm{Si}$ substrates are quite different. We obtained vertical $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ nanosheets on $\mathrm{Si}{\mathrm{O}}₂/\mathrm{Si}$ and sapphire substrates with surface dangling bonds, while we obtained horizontal $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ nanosheets on mica without surface dangling bonds. A continuum model based on surface diffusion and a moving boundary is developed to describe the intermediate states of the steps and the edge. The dangling-bond-assisted heterogeneous nucleation mechanism is proposed to describe the growth of vertical $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ nanoplates: difficult diffusion of $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ adatoms on dangling-bonded substrate surface due to large interface energy between $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ adatoms and $\mathrm{Si}{\mathrm{O}}₂/\mathrm{Si}$ (and sapphire) substrates results in $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ seeds growing perpendicularly to the substrate; then vertical nanoplates inherit the growth direction of $\mathrm{I}{\mathrm{n}}₂\mathrm{S}{\mathrm{e}}₃$ seeds. This work paves the way for the growth of monodisperse vertical two-dimensional nanoplates on $\mathrm{Si}{\mathrm{O}}₂/\mathrm{Si}$ substrates, and it expands their utilizations from conventional lateral structured devices to nonplanar vertical electronic and optoelectronic devices.