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1. For the BJT in Problem #1, let VEB = 0.5 V and VCB = - 2.0 V. In what mode of

ID: 1847209 • Letter: 1

Question

1.

For the BJT in Problem #1, let VEB = 0.5 V and VCB = - 2.0 V. In what mode of operation is the BJT? Sketch the energy band diagram with respect to the equilibrium band diagram. Use concepts learned for the PN junction, i.e. use the base region as the reference (keep it stationary) and change the Emitter Base junction and Base/Collector junction accordingly from their equilibrium conditions. Sketch the minority carrier concentrations in the collector, base and emitter with respect to their equilibrium values. Just as above, consider the BJT as two diodes; one forward biased and the other reverse biased. What is the energy barrier for the diffusion of holes from collector to base? What is the energy barrier for the diffusion of holes from emitter to base?

Explanation / Answer

A answer

BJT always works in active mode

With Emitter- Base forward bias and Base -Collecter reverse biased.

B answer

pnp transistor in active mode

Active mode:

E/B junction forward biased

B/C junction reverse biased

C answer

Energy band diagram of a simple NPN bipolar junction transistor under equilibrium showing electron energy versus position. The depletion regions of the emitter-base and base-collector junctions are marked. Ec is the conduction band,Ef is the device fermi energy level, Ei is the intrinsic Fermi level of the undoped semiconductor, andEv is the valence band.

D answer and E answer: