Complementary Profiles Research Articles

Base transport factor calculations for transistors with complementary error function and Gaussian base doping profiles

By taking account of the carrier mobility degradation at high impurity concentrations, the high-frequency base transport factor of an n-p-n germanium base transistor was computed numerically for different base doping levels. The doping profiles under consideration were Gaussian and complementary error functions. The base doping level adjacent to the emitter was optimized for minimum base transit time. The optimum values are 4×1017atom/ cm3for complementary error function profile and 2×1017atom/cm3for Gaussian profile. The effects of emitter barrier capacitance, base resistance, collector barrier capacitance, and the collector depletion layer on the overall frequency response of a junction transistor are also discussed.

Analytic evaluation of diffused impurity layers in silicon

An analytic method is outlined for the calculation of average conductivity of diffused layers in silicon for a complementary error function and Gaussian impurity profiles and the results are found to be in good agreement with those obtained by the numerical integration method. It is shown that the results for Gaussian distribution are obtained directly from the derivations for an error-function distribution. The method is also useful for the estimation of the temperature coefficient of the diffused layers.