Quantum Confinement of Si Nanosphere with Radius Smaller than1.2 nm

Abstract

We calculate the density of states, the squared optical matrix elementalong the x direction, and the band gap of Si nanosphere withradius r smaller than 1.2 nm using the method of linearcombination of atomic orbitals. It is shown that the quantumconfinement effect of Si nanocrystals exists obviously, fulfilling E = 1.92+0.23/r1.8, but the band gap exhibitsfluctuation with nanocrystal size, which is caused by the danglingbonds of atoms in outer layers. The obtained result indicates that thesurface chemical bonds have larger influence on the energy bandstructure of Si nanosphere when its radius is smaller than 1.2 nm.