The mystery of semiconductors seems a bit difficult to understand, but it can be buttressed to a simple concept. Elements with a full outer band will exchange electrons on the basis of resistance governed by the acreage offered by each bond to the external world. This is the basis for the point contact transistor by Walter Brattain and John Bardeen. Shockley took this concept forward by doping semiconductors with help from his lab people.
All of the elements in the yellow column, above, are in electron balance that is they can be pushed in either way without resistance. That electron will travel in the direction of least resistance.
The elements in the orange and green columns when bonded in a sandwich will have a spare electron in the green column and those in the orange column will lack one. They present ‘Troll Crossing” where an electron traveling from the green column will have an easy task in moving while an electron in the orange column will be repelled by the extra electrons in the green column. When this is done by diffusing elements in columns orange and green into adjacent areas of a semiconductor (Silicon, Germanium or Arsenic) surface, regions with excess electrons and those with a surfeit will pass electrons from the excess to those lacking. The unification process produced is called doping. Semiconductors can be doped from both the yellow and blue columns, but the amplification factor is less dramatic.
That’s it for tonight. I can carry on in comments or a future thread,
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