Thermionic emission limited recombination in phosphorus-implanted polysilicon emitters

Bipolar transistors with P-implanted polysilicon emitters have been fabricated with high emitter efficiency and low emitter series resistance. Temperature-dependent measurements showed that the base current was limited by thermionic emission over a potential barrier of 220 MeV at the polysilicon-monosilicon interface. Due to this effective barrier, the base current was dominated by recombination in the monosilicon emitter. A model which explains the base current and its dependence on the temperature is presented. The difference between the P-doped and As-doped transistor is attributed to the fact that for the latter the base current is not limited by thermionic emission.<
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