The n-type dopant elements on silicon The n-type dopant elements on silicon are phosphorus, arsenic, and antimony from the group V elements. My question is that what is the difference between doping P, As, or Sb? How do we decide to dope whether P, As, or Sb?
Payman
 A: That is a very tricky question! If you're just interested in bulk Si (e.g. a blank Si wafer), then all the dopants basically do the same thing.
The real choices come in if you want to make a device like a transistor, where the doping is not uniform, you may have heat the device during fabrication, you'll have different materials in the devices (including metals and oxides), etc. When faced with all those considerations, the choice of dopant (and how it is added to the Si) is kind of black magic. (Or, at least it seems that way to me.)
For example, one of the ways the dopants differ is how easily they diffuse in Si. So, if you put the dopants in part of your device, but then you need to heat the device significantly in a later fabrication step, then dopants will diffuse out of the region where you put them. If that's a problem, you'll want to choose dopants that diffuse more slowly (generally, that means further down the periodic table).
Another consideration is what other materials will be in the device. Some dopants don't play well with certain materials, and you'll need to take that into account.
There are many more considerations when choosing a dopant. I'm sure there are more detailed resources out there, but from what I've seen, the people who make these choices often rely heavily on experience.
