p type and n type

[Kevin Weddle]

I think that sometimes authors are confused about how to explain electrons and holes. I have read that holes don't move, and I have read that holes are pushed into the n type material. I think it is easier to explain from the viewpoint of atomic structure. P type material is made such that there is left a vacancy in the valence shell of the silicon when the boron is bonded to it. This creates an affinity for any electron that might be nearby. The only movement you have are the electrons as they jump to fill this vacancy. Electrons can go anywhere. They can go into or out of the substrate if there is reason to. The n type material is made such that there is an extra electron sent into the conduction band because the valence band of silicon is filled up when the silicon is bonded to phosphorous.

Many authors create what I call a ying yang when trying to explain how voltage affects the conductivity of n type and p type material. Repel an electron here, push a hole there, create this, narrow that, positive here, negative there. They even compund the problem when they leap from there simple explainations to explaining phenomenon that is just totally bizzare. Are we really ready to go from the simple to the extreme?

 

[V8meathead]

Malvino's Electronic Principles does a good job of explaining the concept.