On Thu, 02 Jun 2005 18:45:58 -0700, Asad wrote:

HI,

How can I perform doping of silicon manually?

Asad

I don't think you can. I'm struggling to remember how it all works. I
think the initial doping is done by the people who make the ingot. Making
an ingot is pretty involved. You would have a very high utility bill if
you decided to make an ingot yourself. But maybe you could buy ingots.

So, let's say it is a P-type ingot. Now you have to create N-type
pockets in order for it to be useful. I think there are two main ways
to do this. (I'm trying to remember. It's all a bit hazy.) I believe
the normal way is that they mask off areas which are to remain P, and
leave the N areas unmasked. Then they heat the wafer and allow N-type
dopant to diffuse in. Like I say, it is all kind of hazy.

There would then be additional rounds of masking and diffusing where you
convert part of your new N-type well back into P-type material (that's
your base). And then there are also metalization steps. Then you would
have to somehow attach leads to the metalized areas. It just seems too
painful, and it's not like would be able to make anything fancier than the
stuff you can buy.

Also, I do remember that nasty chemicals are involved, and the process
control details are critical. Time, temperature, concentration/pressure.
Clean rooms.

--Mac