Turkish Journal of Physics

A Real Space Approach to Si Quantum Dots




Optical properties of Si quantum dots and single vacancy energetics in crystalline Si are investigated using the higher-order finite difference pseudopotential method. The calculations are performed in real space on spherical bulk-terminated clusters containing up to 15 shells of Si that are passivated by hydrogens at the boundaries. In the quantum dot study, the size dependence of the band gap is calculated and compared with available calculations. Quantum confinement effects in polarizabilities and dielectric functions are also investigated. In the vacancy study, by representing the Si crystal as a large cluster, atomic relaxations and energetics associated with a single vacancy in various charge states are examined. It is shown that the vacancy in a quantum dot exhibits a negative U character.

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