On Sat, 04 Jun 2005 09:47:36 GMT, Matt Giwer
wroth:

Asad wrote:
HI,

How can I perform doping of silicon manually?

You can't.

I remember that back in the late 50's that Bell Labs was distributing
science project kits to schools to promote education. Remember that this was
back when the US was playing catch-up to the Russians.

One of the lits was put together to allow school kids to make silicon
solar cells right in the classroom with ordinary stuff found there. The kit
included silicon wafer slices, some chemicals, a 115 volt heating element
similar to the ones used in small radiant room heaters, some asbestos sheets for
insulation, some fine carbide sandpaper, and a list of instructions.

You built an oven from the heater and the asbestos sheets. The heater
was a ceramic cylinder with nichrome wire coiled around the outside and an
Edison screw base. The inside of the cylinder was open and you broke the
silicon wafer into pieces small enough to fit inside.

The wafer pieces were dipped into a water slurry of the chemical, I
forget exactly which chemical (probably something with phosphorous in it), and
placed in the heater/oven to get red hot. The original wafer pieces were
probably grown with an N or P dopant and the subsequent difusion created a
complemental doping.

The wafers were allowed to cool and then the carbide was used to remove
the surface on one side of the wafer to get back down the original silicon. I
forget exactly how the wires were added to each side, probably a loose flat
spiral of bare copper held in contact mechanically. When finished the kids had
a working solar cell.

My brother was given the kit by his science teacher to put together on
his own for "extra credit". I suspect the teacher just wasn't up to the task of
using the kit the way it was intended. I got the kit and played around with it.

So, in short, you CAN manually dope silicon without Billions of dollars
of equipment. I know because I've done it.

Jim