Chemical Forums
Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: rtg72a on November 23, 2013, 10:59:45 AM
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Hi, I am trying to dope my Silicon wafers with a p-type dopant to make some DIY transistors. I know that boron is used for doping Silicon, but I was wondering, can Aluminum be used instead of Boron since they both have the same number of electrons in their valence shells and thus would leave a hole when 'bonded' with Silicon? And if it can be used, are there any drawbacks to this method?
Thanks!
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I think it can be used like also Gallium and Indium are used.
https://www.google.de/search?q=aluminium+for+doping+silicon&ie=utf-8&oe=utf-8&rls=org.mozilla:de:official&client=firefox-beta&gws_rd=cr&ei=kiWSUtOoM8rYtQbgi4D4BA
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Aluminium is commonly used as a P dopant for silicon. In reasonable concentration, it has exactly the same effect on carrier density.
The main difference is the speed of dopant diffusion in silicon, and the interaction of the various dopants. Bigger dopant atoms diffuse slower. Arsenic for instance is used where one wants the dopant to diffuse very little, say at the abrupt emitter of an HF bipolar.
An other difference, interesting mainly for microsensors and actuators, is the stress and strain induced in silicon by the size of the introduced atoms
For DIY transistors, why not mimick the early technology? They used N-type germanium, as a slab making the base, and alloyed the collector and emitter using indium, which also provided the metallic contacts. Or as an intermediate step, use silicon, but alloy the emitter and collector on a slab making the base.
>30 years ago, Sze had compiled two 500-page books that contained carrier mobilities, dopant diffusion versus temperature and concentration, essentially everything you need to design you project. Get used copies over eBay?