Indirect (band structure attached)

R

In date 4/3/11 15:23:46, karim rezouali wrote:
> Dear,
> 
> Is the material under study (ie, bulk amorphous silicon) has a direct
> electronic  gap or not?
> 
> Karim
> 
> 
> Hello,
> 
> I calculated the band structure of bulk amorphous silicon (64 atoms
> tetrahedrically coordinated). I found an HOMO-LUMO band gap of about 0.7
> eV. Then I performed the OpticalCalculation, but I have that the resulting
> imaginary dielectric function has a peak at E<0.7. How is this possible? I
> expect that each valence-to-conduction transition must be larger than the
> bang-gap!
> 
> Roberto

<<attachment: a-Si_bands.png>>

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