Semi-conductor theory and stuff

[Ragnarak]

I have a problem i just can't get my head around and wondered if anyone here had any ideas.

 

We have a set of LEDs and are required to find out what the composition of them is.

 

They are made up of a mixture of Aluminium, Gallium and Indium but we don't know in what proportion.

 

There are 3 different LEDs that give three different colours; red, yellow and green.

 

These 3 all have a different mixture of Aluminium, Gallium and Indium.

 

Is there any way that anyone could suggest to determine the exact composition.

 

So far we've found the band gap energies via several methods. Spectroscopy and IV characteristics have both given us values for the energy gap but we're not sure how to progress from there.

 

Any help would be greatly appreciated

[fafalone]

Melt completely, put it in a centrifuge. This will seperate all the elements. Then you'll know the proportions. But it seems like whoever assigned the problem is going for a more complicated route

[Ragnarak]

indeed

 

 

at the minute we don't want to break it as it's completely encased in the plastic (?) case

 

if we were able to break it we could measure the dimensions of the semiconductor and then apply capacitance/conductivity equations to it

 

this along with the data we have wouldmean we could get 2 3D graphs which would have 3 intersecting planes that would then yield the composition for a single va,ue of energy gap

 

but it means breaking open and potentially damaging the diode :/