Analysis of bipolar junction transistors with a Gaussian base-dopant impurity-concentration profile

A method for a quantitative charge-control analysis of bipolar base-junction transistors with a Gaussian dopant impurity-concentration profile is demonstrated. Analytical expressions for the base transit time are given for two different Gaussian impurity-concentration profiles with the peak concentration at the edge, and within the quasi-neutral base layer. It is also shown that approximating the Gaussian profile by a simple exponential profile results in only an insignificant error in the charge-control analysis.