Consider a PNP BJT optimum designed for low voltage high current gain.
(a) Draw energy band diagram with proper labeling with VCB= -0.7V, VEB= 0.7V. Which mode is the BJT operated in?
(b) Plot excess minority charges stored in each region with proper labeling for the BJT biased in (a).
(c) If the voltage capability of the BJT needs to be increased, which layer(s) should have a higher doping density and which layer(s) should have a lower doping density? Why?
(d). If the BJT is now biased into reverse active mode, draw the energy band diagram and label majority and minority carrier activities in the emitter and collector junction regions.
(e). How will the BJT's current gain and breakdown voltage be changed in reverse active mode in comparison to that in normal active mode? Why?