What happens to the electrons in the N region of the collector of npn transistor that operates in active mode ?

I know that electrons coming from emitter split to base current and collector current , i am asking about electrons in the N region of the collector due to doping , do they add to collector current ?


1 Answer 1


The electrons leaving the collector are equal to the electrons entering the emitter minus the electrons leaving through the base. Although we usually talk in terms of conventional current: the current leaving the emitter is the sum of the current entering the collector and the current entering the base.

  • \$\begingroup\$ I know that Ie=Ib+Ic .i also know that electrons from emitter get injected to base and they split as collector and base current but i am asking about the free electrons in the N region of the collector and whether they add to electrons comming from emitter or not \$\endgroup\$
    – user207332
    May 16, 2019 at 1:06
  • \$\begingroup\$ @user207332 They do not. If they did, they would quickly run out. \$\endgroup\$
    – Matt
    May 16, 2019 at 1:27
  • \$\begingroup\$ Please , can you expand on this a little more \$\endgroup\$
    – user207332
    May 16, 2019 at 1:30
  • \$\begingroup\$ The "free" electrons that you mention either have a net velocity, which makes them part of the current we've described, or they have no net velocity and they are not part of the current. An electron that is free to move is not necessarily moving. \$\endgroup\$ May 16, 2019 at 10:46

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