High injection in a two-dimensional transistor

Authors:
  • HHH.H. Heimeier
    H.H. Heimeier
  • WEW.L. Engl
    W.L. Engl
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Abstract
A generally accepted theory for bipolar transistors operated at high current densities has not yet been established. Controversy exists as to whether high current Performance is affected primarily by vertical or lateral phenomena. This paper solves the high injection problem by means of a two-dimensional numerical algorithm. The results of some calculations pertaining to a particular example show that base push-out is clearly the dominating mechanism. Emitter crowding caused by lateral majority-carrier current flow in the active base is moderated by base conductivity modulation; it is, however, not negligible. The major limitation of the present work results from the fact that high doping effects are not considered. Thus accurate hFEpredictions cannot be given.