I would like to ask question about the resistance of a diode under different regime. Surely, in reverse bias, it has a breakdown voltage, and in forward bias,it rises exponentially according to the exponential relationship according to the theory ( ideal Shockley diode equation ) . But what happens at the flat band situation? I do not understand why it should obey Ohm's law well when the fermi levels are split by eV=eVo, where Vo is the barrier height (when applied bias V is zero). (see Fig.1.)
Any Justifications with the physics of the charge carriers or using formulas would be much appreciated.
Thanks