- #1
pvshackguy
- 10
- 0
Most explanations of doping, coupled with the simple definition of hole as positive charge carrier, and reinforced by classic graphic illustrations of P- and N-doped regions full of little plus and minus signs respectively, makes for a common point of confusion when learning basic semiconductor theory.
When it is explained that p-doping introduces holes and n-doping, electrons, it is easy for the unwary student to conclude that the p-doped region therefore attains a net positive charge and the n-doped region a net negative charge. This is clearly not true, as there are in each case a balanced total of electrons and protons and no net charge. Yet even the author of a textbook I have in my hand falls directly into this trap.
So how to distinguish e.g. between the "holes" introduced by p-doping and charged holes diffusing through the material? Do we speak of "neutral" holes ("empty" holes??) vs. charged holes? I have never seen a formal distinction in my searches through books and web sources, yet the difference seems clear enough to me.
Further, can we quantitatively distinguish between the attraction between a free electron and a "neutral" hole vs. a "charged" hole? In my amateur view it seems that a charged hole (i.e. associated with a positive ion) must surely be more attractive than a "neutral" hole (associated with an electrically-neutral formation of silicon atoms bonded to a single p-dopant atom) which, relatively, just seems like a nice place for an electron to be.
I hope I haven't embarrassed myself too badly. I beg your forgiveness.
When it is explained that p-doping introduces holes and n-doping, electrons, it is easy for the unwary student to conclude that the p-doped region therefore attains a net positive charge and the n-doped region a net negative charge. This is clearly not true, as there are in each case a balanced total of electrons and protons and no net charge. Yet even the author of a textbook I have in my hand falls directly into this trap.
So how to distinguish e.g. between the "holes" introduced by p-doping and charged holes diffusing through the material? Do we speak of "neutral" holes ("empty" holes??) vs. charged holes? I have never seen a formal distinction in my searches through books and web sources, yet the difference seems clear enough to me.
Further, can we quantitatively distinguish between the attraction between a free electron and a "neutral" hole vs. a "charged" hole? In my amateur view it seems that a charged hole (i.e. associated with a positive ion) must surely be more attractive than a "neutral" hole (associated with an electrically-neutral formation of silicon atoms bonded to a single p-dopant atom) which, relatively, just seems like a nice place for an electron to be.
I hope I haven't embarrassed myself too badly. I beg your forgiveness.