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silicon/polysilicon emitter
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Tuen
Nov 25, 2008, 6:22:48 AM11/25/08
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When we're building BJTs with polysilicon emitters, why is it still
necessary to have the thin layer of crystalline silicon at the emitter-base
contact? That is, why can't we make the entire emitter out of polysilicon?
The low mobility would still serve to reduce I_b, and the high dopant
density would still inject relative high amounts of carriers into the base,
right?
necessary to have the thin layer of crystalline silicon at the emitter-base
contact? That is, why can't we make the entire emitter out of polysilicon?
The low mobility would still serve to reduce I_b, and the high dopant
density would still inject relative high amounts of carriers into the base,
right?
Daniel C. Huang
Nov 29, 2008, 2:57:30 PM11/29/08
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It forms a poor contact to the base.
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