Ebers–Moll model aF? Where does it come from?
αF is not the Hfe of the transistor. Per the model, αF of the emitter current reaches the collector. 

This means that αF of the diode current passing through the base-emitter junction contributes to the current flowing through the base-collector junction. 

Typically, αF has a value of between 0.98 and 0.99. the forward beta (~hfe) is αF/(1-αF).