Current-gain enhancement in lateral p-n-p transistors by an optimized gap in the n+buried layer

A two-dimensional electrolytic tank analog study simulating volume recombination in the base region of lateral p-n-p transistors is presented. The effect of an n⁺buried layer is studied and it is found that a proper gap in this layer gives rise to a lateral transistor with common-emitter current-gain factor higher than that which can be achieved if the n⁺buried layer extends throughout the region below the transistor. This result is found to be true for various combinations of base geometry and minority carrier lifetimes which have been simulated. The analysis of the high-frequency performance shows that the gain-bandwidth product of the lateral p-n-p transistor is also maximized by providing an optimum gap in the buried layer.