# How to find the degree of doping in a material?

I find this term a bit mysterious, it appears that everyone is using it intuitively without proper definition (or at least I failed to find one).

So the Physics Glossary defines it as

In condensed matter physics, doping refers to the deliberate introduction of impurities into an extremely pure crystal. For example, a crystal of pure silicon might be doped with boron atoms that change the material's electrical properties, making it a more effective semiconductor.

But this definition doesn't help to use it in practice. Books like "Physics of Low-Dimensional Semiconductors" by Davies keep using this term a lot as "you can control something with doping" or "something is limited by doping". Professors assign problems mentioning "(...) find doping (...)".

What is doping in practice in this kind of context. Is it a number? Is it a function? What are its dimensions? If we have to find the degree of doping, what do we search for?

• Doping is a physical process. It isn't something you calculate or something that has a number associated with it like mass or momentum. You can quantify things about the doping, but that is different than doping itself being a number or having dimension. – Aaron Stevens Oct 19 '18 at 3:59
• I think that many books and articles like the following one explain what doping is: en.wikipedia.org/wiki/Doping_(semiconductor) – Samuel Weir Oct 19 '18 at 4:00
• I understand this is something more complicated than just a value, perhaps I should formulated my question as, if someone asks you to "find doping", what do you need to find? – Marek Oct 19 '18 at 4:57
• @Marek - "Find doping" means find the numerical value of the required doping for whatever physics problem was given to you. – Samuel Weir Oct 19 '18 at 5:03
• @SamuelWeir ok, so it is a value, and what are its dimensions? – Marek Oct 19 '18 at 5:09

In intrinsic crystalline silicon, there are approximately $$5×10^{22} \text{ atoms}/cm^3$$. Doping concentration for silicon semiconductors may range anywhere from $$10^{13} cm^{−3}$$ to $$10^{18} cm^{−3}$$.
The doping level is a concentration of dopants in a semiconductor - as such it has the unit $$[\frac{1}{cm^3}]$$, since it gives the number of dopant atoms per volume.