|
|
Physics of Semiconductor Devices |
|
|
Exam March 2007, Problem 3The base of a pnp bipolar transistor is grounded. A battery is connected between the emitter and the base. Another battery is connected between the base and the collector. This is known as the common base configuration. (a) Draw the circuit indicating the polarities of the batteries that would put the transistor in the forward active mode. Explain why you have chosen these polarities. (b) Plot the minority charge density in the emitter, base, and collector indicating whether electrons or holes are the minority charge carriers. (c) Why is the emitter more heavily doped than the collector? (d) How do the carriers that are emitted into the base reach the collector? |