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Using electronic-structure calculations and the concept of "fuzzy" band structure of finite-size crystals, we showed how the charge transfer from the core to the surface of silicon nanocrystals can be optimized by choice of organic ligands to maximize the probability of radiative transitions (luminiscence). Fabrication of efficient light sources out of silicon or other indirect bandgap semiconductors (C, Ge) will enable integration of photonic devices into existing microprocessor architectures.
Description
Symmetric nanoparticle with its crystalline core made of 232 silicone atoms (2 nm diameter) covered by various covalently bonded organic ligands (hydrogen, aliphatic hydrocarbons, fluorinated aliphatic hydrocarbons). The intensity of the blue color represents electronegativity of atoms, which causes formation of electrostatic field and charge transfer from core to surface. By this mechanism, the wavefuctions of holes and electrons in the crystal are modified in such a way that radiative recombination of an electron and a hole is no longer forbidden unlike the bulk material.
Contact person: Ing. Prokop Hapala, Ph.D.
Collaborating institutions:
University of Amsterdam, Netherlands,
Italian Institute of Technology, Genova, Italy