Science & Technology Quiz 2: The one with the catchy title.

[uppi]

YBCO is about 90 K, but I think we can do better than that. I'd say about 120 K

 

[qwertz]

it's actually 134K and the material is a thallium-mercury-copper-someting-oxide..., but 120K isn't that far away, so uppi's up

 

[dido]

-50c/223k?

 

[uppi]

What is the (current) definition of a semiconductor?

 

[Olleus]

A material which allows charge (usualy electrons but ions should be possible too) to flow in one direction but not in the opposite direction?

 

[Mise]

Is it any material between a certain level of conductivity? Or an average number of valence electrons between X and Y at room temperature? (I'd guess X and Y would be very very small...)

 

[Firstlady]

Any material that does not conduct electricity as well as a good conductor?

 

[Perfection]

A material with a relatively small gap between it's valence and conduction bands for electrons. Insulators have a large gap, and conductors have no gap.

 

[uppi]

A material which allows charge (usualy electrons but ions should be possible too) to flow in one direction but not in the opposite direction?

No. That would be a diode.

Is it any material between a certain level of conductivity?

That has been used as definition but was abandoned, because you'd have to adjust the boundaries every time someone found a new material with semiconductor properties that exceeded these boundaries.

Or an average number of valence electrons between X and Y at room temperature? (I'd guess X and Y would be very very small...)

Valence electrons are not significantly affected by (room) temperature. If you mean electrons in the conduction band, then it would only be a fancy way of saying something about the conductivity.

Any material that does not conduct electricity as well as a good conductor?

That would include insulators.

A material with a relatively small gap between it's valence and conduction bands for electrons. Insulators have a large gap, and conductors have no gap.

This works for the classic semiconductors, but for exotic ones, like diamond this doesn't really work.


But you're all on the right track, it is related to conductivity.

 

[Firstlady]

Any material that does not conduct electricity as well as a good conductor but conducts electricity better than an insulator. That's still kind of vague. I don't know.

 

[Mise]

Any material that does not conduct electricity as well as a good conductor but conducts electricity better than an insulator. That's still kind of vague. I don't know.

So... anything that's not a conductor or insulator?

Err... my guess... A material whose conductivity increases dramatically when a dopant is introduced?

 

[uppi]

So... anything that's not a conductor or insulator?

Err... my guess... A material whose conductivity increases dramatically when a dopant is introduced?

Yes, that's it. The ability to manipulate the conductivity with dopants is what makes semiconductors special.

Your turn.

 

[Mise]

Why might a semiconductor be aromatic?

 

[SS-18 ICBM]

Either aromatic compounds are used as dopants or their resonant structures allow electron flow consistent with that needed for a semiconductor.

 

[Mise]

Can you be a bit more specific?

 

[SS-18 ICBM]

Can you be a bit more specific?

Unfortunately, that's as specific as I can get.

 

[Mise]

Well if no-one else can either then you can have it I'll give it 24 hrs.

 

[GoodGame]

The obvious guess would be that an aromatic is based on the benzene ring which is very good at redistributing electrons, which is what I think SS-18 was getting at.

 

[Mise]

Sod it, SS-18 can have it! I was looking for the fact that the aromatic compound had to be part of a polymer chain, and it had to be doped. A lot of research is being done on organic semiconductors, particularly in solar cells, where it promises cheap, large scale electricity generation.

 

[SS-18 ICBM]

Describe a few ways of how Ebola infection can kill you.