Why don’t two diodes connected anode to anode (or cathode to cathode) function as PNP or NPN transistors?
Simple diodes are PN junctions that prevent electron flow in one direction through the negative charge and (some) transistors are PNP or NPN with two PN junctions so why cannot I use two diodes connected cathode to cathode or anode to anode (so that two anodes or two cathodes present on both sides) to replace a transistor/do not work that way?
Edit: Just reread the rules and it says that the question must be clear from the title (but I can’t change it) so I’ve put it on the first line.
In: 5
Two diodes back to back are not PNP. It’s PN(Metal)NP. A semiconductor metal junction does not behave the same way as if the metal were not there.
Furthermore, the thickness and doping strength of each layer in a BJT is very specific. If you change those parameters, the transistor will perform very differently (or fail to perform). The PN junctions in diodes are tuned for different properties and applications.
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