Hello ! I just discovered in an old document (Dupont Nemours 1952) that Shockley Law is also available for thermionic diode with inverted bias (plate < cathode), this for low currents < 200 µA, and before space charge appears (Child-Lagmuir). I'm very surprised, where is Fermi level ? where are N & P ? If someone knows a demonstration of this, thanks by advance.