Application to Silicon Quantum Dots, Wires and Slabs

APPLICATION TO SILICON QUANTUM DOTS, WIRES AND SLABS 

The dangling bonds at the surface were eliminated by saturation with hydrogen. This is essential, otherwise the gap would be completely masked by the dangling-bond localized surface states. Experimental silicon samples also have a surface passivation, 

For this study the density functional method was applied at its local approximation level. An application of the density functional to absorption and luminescence involves excited electronic states. As in any electronic structure theory, excited states are conceptually more difficult to treat than the ground state, since there is an orthogonality requirement with respect to all lower states. Despite the fact that DFT was originally designed to efficiently calculate electronic ground states, several extensions have been developed to treat excited states for a review see Jones and Gunnarsson [99]. 

A discussion of transition matrix elements as a function of characteristic size has been given in [93]. Basically the optical transition matrix element falls off rapidly in larger structures. 

The band gap shows a rather smooth variation with characteristic structure size. Fig. 6 shows band gaps for spherical silicon cristallites (dots), wires and slabs. The 

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