"D. C. current amplification factor of junction transistors"

In the design of transistors for class B amplifier and switching applications, a primarily important parameter is the DC current amplification factor. By extending the work of Shockley, Webster and Rittner, a theoretical expression has been derived for the variation of this DC current amplification factor versus emitter current at high injection levels. Calculations have been made based upon this theoretical expression. Results are presented for emitter currents up to the amperes range with different values of resistivity, life time, width and surface recombination velocity of the base region, and different values of conductivity and diffusion length of the emitter region as well as the size of the emitter-base junction. These results provide a quantitative guide for the design of power transistors.