Band-edge states in ultrasmall silicon quantum boxes: calculations of electronic states and oscillator strengths

Band-edge states and oscillator strengths in four configurations of ultrasmall Si quantum boxes (QBs) with (100) planes saturated by H have been calculated using the extended Huckel-type non-orthogonal tight-binding method. It is found that, while the valence-band edge states are always bulk like, both bulk-like and surface-like states occur at the conduction-band (CB) edge, depending on the atom configuration of the QB studied. An analysis shows that the surface-like CB edge states are caused by an interhydride interaction between trihydride units on the hydrogenated QB surface and there is significant correlation of oscillator strength with the CB edge states.