申論題

4.The common-base current gain a of an NPN BJT can be expressed as a = γa_Tδ where a is the emitter injection efficiency factor, a_T  is the base transport factor, andδ is the recombination factor. To have an a as large (close to 1) as possible, cach of these factors must be close to l as well. For these three factors, respectively, what about device design and/or operation bias must be done to make them large? (15%) If is increased, will a increase or decrease? Why? (5%)