Semiconductors -- role of displaced Silicon or Germanium

Thread Starter

logearav

Joined Aug 19, 2011
248
Revered Members,
When we dope a pure Germanium or Silicon with pentavalent impurity or trivalent impurity, the dopant replaces Silicon or Germanium and bonds with neighbouring Si or Ge atom. That is Dopant takes the centre position and bonds with 4 neighbouring atoms.
Now where do that replaced Si or Ge go in the crystal?
 

Wendy

Joined Mar 24, 2008
21,840
The dopant is usually 1 part per million, so your concept is a bit off. Just a very small dab will do you.
 

thatoneguy

Joined Feb 19, 2009
6,349
I believe if you add too much doping, you end up with a conductor or insulator, rather than a semiconductor.
 

Adjuster

Joined Dec 26, 2010
2,147
I think the OP is referring to the physical rearrangement of the basic atoms in the material, for instance if a silicon crystal is doped.

In the case of alloying or difusion processes, I would guess there is a general shuffling about of atoms, so one would no more ask where the silicon had "gone" than where the iron atoms might "go" when additives are introduced to alloy steel.

Perhaps somebody better informed could comment on modern ion implantation processes. Are these normally followed by diffusion or annealing processes to "heal" the crystal?
 
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