Nolan, M,O'Callaghan, S,Fagas, G,Greer, JC,Frauenheim, T;

2007

January

Nanoletters

Silicon nanowire band gap modification

Validated

()

AUGMENTED-WAVE METHOD OPTICAL-PROPERTIES ELECTRONIC-PROPERTIES QUANTUM WIRES SURFACE NANOCRYSTALS CONFINEMENT TRANSISTORS TRANSPORT GROWTH

7

34

38

Band gap modification for small-diameter (similar to 1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct band gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the band gap, resulting in relative energy shifts of up to an electronvolt. The band gap shifts are traced to details of the hybridization between the silicon valence band and the frontier orbitals of the terminating group, which is in competition with quantum confinement.

DOI 10.1021/nl061888d