| 초록 |
Since the discovery of graphene, growth of two-dimensional (2D) nanomaterials has greatly attracted attention. However, spontaneous growth of atomic two-dimensional (2D) materials is limitedly permitted for several layered-structure crystals, such as graphene, MoS2, and h-BN, and otherwise it is notoriously difficult. Here we report the gas-phase 2D growth of non-layered structure materials such as silicon (Si) and germanium (Ge), that is cubic in symmetry. Freestanding-, single crystalline 2D Si and Ge nanomaterials can be grown on the substrates under a diffusion limited aggregation (DLA) environment via dendritic growth and an interdendritic filling mechanism and to form a Si or Ge nanosheets (NSs). These 2D nanomaterial showed unique properties that comes from 2D nature on a nanometer scale. For examples, thin SiNSs show strong thickness-dependent photoluminescence in visible range including red, green, and blue (RGB) emissions with the associated band-gap energies ranging from 1.6 to 3.2 eV; suggest practical implications for novel 2D Si nanophotonics. SiNSs also showed high capacity and excellent capacity retention without fracture or cracking of the material as anodes for lithium ion batteries (LIB). Importantly, reversible crystalline-amorphous phase transformations are observed along with the intercalations that makes SiNSs as a promising candidate for reliable high-performance LIB anode materials. The 2D growth of cubic-structure crystals in our CVD process under DLA environment will be discussed in details with some examples for other non-layered structure crystals to form 2D nanomaterials. |
