I have a plot log (I) = f(U) for a few diodes: Silicon diode, Germanium diode, some LED and a Zener diode. I need to determine the material, from which the Zener diode is made based on the positioning of its characteristics. What parameter should I look for to determine it? I thought about checking the band gap somehow, but I am not sure whether it can be determined by just having a plot log(I) = f(U).
And if I know the difference between voltages (for specified current) of two diodes , let's call them A and B, and I have some information about diode A (including its band gap), can I calculate the band gap of the B diode?