Why amorphous phase materials have wider bandgap?

[sttan]

I'm wondering why the amorphous phase materials have wider bandgap compared to its crystalline phase. To my best knowledge, the bonding mechanism does not changed as the material transform from crystalline phase to amorphous phase. So what causes it has larger bandgap?

ST

 

[marlon]

I'm wondering why the amorphous phase materials have wider bandgap compared to its crystalline phase. To my best knowledge, the bonding mechanism does not changed as the material transform from crystalline phase to amorphous phase. So what causes it has larger bandgap?

ST

I think (not to sure though) it has something to do with the fact that the periodic Bloch wave-functions do not account for the forbidden energy as much as they used to in a cristal-lattice.

The band gap is there because the electrons can acquire two different potential energy-values when passing through the periodic potential of the positive lattice ions

regards
marlon

 

[kurious]

Look at:
http://www.wordiq.com/definition/Solid_state_physics

perturbation theory is needed.

 

[sttan]

Thanks to Marlon and Kurious...

ST

 

[Pieter Kuiper]

Search for "Anderson localization" and "band edge states".

 

[winewind]

I'm wondering why the amorphous phase materials have wider bandgap compared to its crystalline phase. To my best knowledge, the bonding mechanism does not changed as the material transform from crystalline phase to amorphous phase. So what causes it has larger bandgap?

ST

Are you sure amorphous materials have wider bandgap? I think they should have narrower Eg due to the band edge tailing effect.