Seed-Induced Vertical Growth of 2D Bi2O2Se Nanoplates by Chemical Vapor Transport

As two-dimensional (2D) layered materials attract more attention owing to their unique optical, electrical, and thermal properties, there are persistent efforts to grow high-quality 2D layered materials for fundamental research and device applications. While large-area 2D layered materials with high crystal quality can be obtained through chemical vapor transport, the strong binding between 2D layered materials and substrates poses a significant challenge for attempts to reveal their intrinsic properties and to use these 2D building blocks for constructing advanced heterostructured devices. Therefore, it would be ideal to grow high-quality 2D materials with minimized contact and binding with substrate. Through both calculation and experiment, it is demonstrated that by introducing a seed layer at the nucleation stage, the crystallographic disregistry and the corresponding adhesion energy between 2D materials and substrate can be altered, resulting in a change of crystal surface in contact with the substrate, and therefore vertical growth of 2D materials on substrates. As an example, it is demonstrated that with Bi2O3 serving as a seed layer, vertical growth of 2D plates of Bi2O2Se on mica substrates can be realized. These vertically grown 2D nanoplates of Bi2O2Se can be conveniently transferred with their thermal properties investigated for the first time.