18-05-2017, 06:46 AM
(17-05-2017, 07:43 PM)Nowhere-Man Wrote: They are not free electrons. As desribed in a scene of the 50's Attack Of The Crab Monster, "the electrons jump from atom to atom".
Nonsense. Electrons (and holes) in semiconductor lattices behave according to Fermi-Dirac statistics. Statistics because there is a large enough density of them. Indeed the conduction process in doped p-n junctions is completely understood in terms of where the Fermi level is in relation to the dopant energy states near the conduction and valence band edges.
Take it further to superconductors, where paired electrons (cooper pairs) condense at low temperatures way below the Fermi energy. They pair over distances of hundreds of nanometers (so thousands of atomic diameters) and move with zero electrical resistance. Any concept of electrons jumping rather than smoothly flowing is clearly wrong here too.
The only process that could conceivably considered as "jumping" is electron tunnelling. If an energy barrier is higher than the electron energy, and also thin enough, electrons can tunnel though because of their quantum mechanical nature. That is the principle behind the Tunnel Diode. But really even there there is no jumping as such.
