Impact of fluorine incorporation in the polysilicon emitter of NPN bipolar transistors

We demonstrate that fluorine incorporation in the polysilicon emitter of NPN bipolar transistors significantly reduces the current gain h/sub fe/. The gain degradation can be related to a reduction of the barrier to hole transport at the poly-Si/mono-Si interface. In addition to a gain reduction, fluorinated-emitter transistors display lower base recombination currents (at low base-emitter biases) than nonfluorinated emitter devices, suggesting that fluorine passivates recombination centers in the emitter-base space charge region.<
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