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Substitute for Boron in p-type semiconductor? Answered

I am trying to think of ways to make solar panels from scratch.  I can get phosphorus from pee, silicon can be extracted from the rocks all around me, but I don't have naturally occurring boron nearby.  What are some substitutes that can be synthesized from the world without modern factories or laboratories?  Furnaces are not out of the question.


Have you any idea what purity of the silicon and dopants you need is ?

I know, they have to be pretty doggone pure, but I am thinking theoretically. It is just that the materials around us have become very diverse and complex, so I would like to know the processes involved in this facet of the modern world. I don't mean to actually make solar cells.

Well that's not what your queston implies....

The silicon has to be 99.999999% pure AT LEAST, before its enough of an insulator that doping it has the appropriate effect. That said, for solar cells, you can get away with a crappier grade.

The silicon is prepared from extremely pure feedstock, produced by techniques like zone refining, or float zone recrystallisation, where a band of extreme heat is passed very slowly down a long bar of material - in fact, AFAIR, making pure material like that for solar cells is particularly attractlve.

Alternatively, a Czochralski furnace is used to make hyper-pure single crystals of silicon, in 100kg boules !

I am familiar with float zone recrystallization. I am currently working out methods of performing such a process. A Czochralski furnace might be an easier alternative. Would that be used with less pure silicon crystals or just silicates? I am under the impression that a method of extracting silicon from silicates is to heat it to 1400 C in the presence of carbon (charcoal in a bloom furnace?), so that could be a precursor to the Czochralski furnace.

Boron is a pretty common element too.  It is present in boric acid, which is sold as an natural insecticide, and borax which is sold as a laundry soap additive.

If you are capable of obtaining phosphorous from urine, or silicon from dirt...  then obtaining boron from from borax or boric acid should be just as easy, I guess.

However,  I would also guess that doing any of those chemical manipulations, outside of a laboratory, would be very tricky, especially for making semiconductors, since semiconductors are rumored to have properties that are very dependent on even small amounts of impurities.  Besides, if you trying to make silicon-based semiconductors, don't you need a furnace hot enough to melt silicon?  I'm not sure it's the kind of thing you cook in a microwave oven.

But since you are interested in making solar cells, there are some demonstration type tricks for making your own solar cells, and I linked to a bunch of these the last time I answered the "homemade photovoltaic cell" question, um, here:
Some are based on copper oxide, some on titanium dioxide and raspberry juice, some on other materials.  I don't think any of them will produce a solar cell that makes significant amounts of power, but they might provide an interesting demonstration and/or learning experience.

I know its around somewhere, but I don't notice any borax deposits lying around. What environments does borax occur in?

Also, I think a bloom furnace (charcoal inside composite clay structure) would reach high enough temperatures to melt silicon. I may be wrong.

If you mean solar cells, then, much as it pains the Maker in me, I would honestly say "forget it".

That you have to ask these questions show that you do not have the equipment required to make a photovoltaic cell.

Instead, have a stab at optimising the solar battery idea, where solar energy liberates electrons in solution to drive a circuit.

I did mean cells, not panels, forgive me. However, I do not intend to actually make some solar cells, only know how to do so. I understand how advanced the factories have to be; I am trying to bring the techniques closer to the average person.

So, regardless of difficulty of actual cell creation, are there any elemental, polyatomic ion, or other substitutes for boron as dopant?

Not to my ken, but I'm not an expert.

IF it could be done industry would be doing it.


6 years ago

I think you might have more success composting zombies. Solar powered Zombies, remove their solar cells before you shred and till.

You need to do a lot more research.

Boric acid used to be the main component in douche's, I don't know what they use now. Not my field of expertise. However stockpilling bottles of your pee and old douches just might draw some unwanted attention. (it also smells pretty bad after a few days in the sun.)

Start collecting all the little ones from solar calculators and solder them together.