Diffused silicon power transistor characteristics as related to base and emitter geometries

The design of diffused silicon high-speed power transistors is complicated by the absence of a suitable design theory. Calculations using alloy transistor theory predict results at variance with measurements made on double diffused silicon units. This is particularly true of effects dependent on emitter width and lateral base current flow. Existing design theory indicates the superiority of narrow emitters whereas experiment reveals that wider emitters often produce a better compromise between speed and efficiency for high current devices.