BJT working in saturation mode

Question

I have the following circuit.

The transistor is working in saturation mode. It means both p-n-junctions are forward-biased. Thus, there are two diffusion currents in the transistor (electrons move from the emitter and from the collector into the base, the currents of holes from base into the emitter and collector are fewer because of the fewer concentration of impurity in the base). So I expected, that the emitter current and the collector current had been equal. But it is not that in the computer model. The collector current is much greater than the emitter current. Why?

Answer 1

Your circuit is:

^{simulate this circuit – Schematic created using CircuitLab}

which means you bring Q2's emitter and collector to exactly the same potential, so this is identical to:

^{simulate this circuit}

So, your Q2 isn't working as a transistor, but really just as a pair of diodes: The base-emitter junction and the base-collector junction.

There's no need for these two to be identical; in fact, it's pretty typical that the base-emitter junction is better-conducting.