Energy Band Diagrams --Question (1 Viewer)

[AnimeX]

Hi guys, I have a question regarding energy bands.

My teacher said they always (even at 0K) overlapped however according to the HSC sample answers they don't.

Can someone explain this to me please? is this answer from Board of Studies at 0K? or at 273K? cause I believe at 273k the bands are indeed overlapping.

edit: oh sorry guys, I was meant to say I'm talking about the conductor ^

Please explain the concept

NB: this was in 2012 HSC phys paper.

 

[someth1ng]

You probably misinterpreted your teacher or your teacher is mistaken - there's always a band gap except for conductors, where they overlap.

1. The band gaps only overlap for conductors.
2. There's a small gap for semiconductors and a large gap for insulators.

 

[iBibah]

Hi guys, I have a question regarding energy bands.

My teacher said they always (even at 0K) overlapped however according to the HSC sample answers they don't.

Can someone explain this to me please? is this answer from Board of Studies at 0K? or at 273K? cause I believe at 273k the bands are indeed overlapping.

Please explain the concept

NB: this was in 2012 HSC phys paper.

If this was the case we wouldn't have conductors, semiconductors and insulators. In essence it's what defines the three.


Sent from my iPad using Tapatalk HD

 

[AnimeX]

You probably misinterpreted your teacher or your teacher is mistaken - there's always a band gap except for conductors, where they overlap.

1. The band gaps only overlap for conductors.
2. There's a small gap for semiconductors and a large gap for insulators.

so in the sample answer what would be the temperature? is the zero gap overlapping or just touching for the conductor? <-- bit confused there

 

[someth1ng]

so in the sample answer what would be the temperature? is the zero gap overlapping or just touching for the conductor? <-- bit confused there

How is temperature relevant - if a solid is ACTING as a conductor, the band gaps overlap - if a solid is ACTING as an insulator, there is a large band gap - if a solid is ACTING as a semiconductor, there is a small band gap.

The only way temperature is relevant is that if you increase temperature, conductivity of a semiconductor increases and conductivity of a conductor decreases.

 

[AnimeX]

How is temperature relevant - if a solid is ACTING as a conductor, the band gaps overlap - if a solid is ACTING as an insulator, there is a large band gap - if a solid is ACTING as a semiconductor, there is a small band gap.

The only way temperature is relevant is that if you increase temperature, conductivity of a semiconductor increases and conductivity of a conductor decreases.

so in the HSC sample answer, by "zero gap" does this mean overlap in the conductor?

 

[someth1ng]

so in the HSC sample answer, by "zero gap" does this mean overlap in the conductor?

Yes.

 

[RishBonjour]

so in the HSC sample answer, by "zero gap" does this mean overlap in the conductor?

when you draw them out - you should show the overlap in HSC instead of just a zero band gap. But someth1ng explained it perfectly.

 

[luvglee4lyfe]

By zero gap it means no gap not at 0K - the temperature is irrelevant here. i think that is where you got confused.

 

[nerdasdasd]

More info >>
In conductors, the bands connect/overlap meaning electrons can travel across the bands easily.... Thus meaning its ability to conduct electricity is high.

 

[someth1ng]

By zero gap it means no gap not at 0K - the temperature is irrelevant here. i think that is where you got confused.

The band gaps I explained is "at a given temperature" - it can be at ANY temperature, it MAY be 0K but it can also be every other temperature, as well.