It is said that P-Type semiconductors' majority carriers are holes. But based on my current understanding, there should be no extra holes except for those generated by heat (i.e. electron-hole pairs like in intrinsic semiconductors).
Lets assume we have a P-Type semiconductor – Silicon doped with Boron (with an Boron atom in the middle in the image below).
Please correct my wrong assumptions:
- For one chemical bond to take place between 2 atoms we need a pair of electrons (each atom "offers" 1 electron).
- A Boron atom pairs with exactly 3 Silicon atoms. There is one surrounding Silicon atom (the one under the Boron atom in the image above) whose electron doesn't participate in any chemical bonds.
- Both the Boron atom and the Silicon atom under it are electrically negative to the outside and won't accept any other valence electrons.
Where does the majority of holes come from then? Based on my understanding, the P-Type semiconductor should have electrons as the majority carriers (because one electron of the Silicon atom (in the image above) does not bond with the Boron atom) instead of majority of holes and thus should behave like an N-Type semiconductor.