Growth mechanism and self-polarization of bilayer InSb (111) on Bi (001) substrate.

Polarity introduced by inversion symmetry broken along <111> direction has strong impacts on the physical properties and morphological characteristics of III-V component nanostructure. Take III-V component semiconductor InSb as an example, we systematically investigate the growth sequence and morphology evolution of InSb (111) on Bi (001) substrate from adatoms to bilayers. We discovered and verified that the presence of amorphous-like morphology of monolayer InSb was attributed to the strong interaction between mix-polarity InSb and Bi substrate. Further, our comprehensive energy investigations of bilayer InSb reveal that an amorphous first layer will be crystallized and polarized driven by the low surface energy of the reconstructed second layers. Phase diagrams were developed to describe the ongoing polarization process of bilayer InSb under various chemical environments as a function of deposition time. The growth mechanism and polarity phase diagram of bilayer InSb on Bi substrate may advance the progress of polarity controllable growth of low-dimensional InSb nanostructure as well as other polar III-V compound semiconductors.