`Structural relaxation and its effects on photoluminescence properties in Si quantum wires'
J.Koga, K.Nishio, H.Ohtani, F.Yonezawa and T.Yamaguchi
Journal of Non-Crystalline Solids 293-295 630 (2001).
We calculate structural relaxation for a Si quantum wire in order to determine the mechanism of the
efficient photoluminescence (PL) from Si. We find that structural relaxation, which has been ignored in
most previous works, has a strong correlation to the PL properties of Si. The total energy of the
quantum wire is optimized within the framework of the tight-binding (TB) approximation. The resultant
structures for the ground and excited states have different band gaps, which accounts for the
luminescence Stokes shift observed in experiments. We also find that the relaxation greatly improves
the oscillator strength for the transition between band edges, which gives a great improvement in the
luminescence efficiency.
Back
2001/12/10