EFFECT OF GRAIN-BOUNDARY ON MINORITY-CARRIER INJECTION INTO POLYSILICON EMITTER

An improved model of minority carrier injection into polysilicon emitt er has been proposed. Minority carrier recombinations in grain boundar ies and grain boundary thickness are considered simultaneously. Minori ty carrier mobility and lifetime as a function of polysilicon thicknes s are introduced. Not only a conclusion that the grain boundary blocks and recombines minority carriers is obtained, but the contributions o f different grain boundaries to minority carrier injection saturate cu rrent densities are distinguished. The minority carrier injection satu rate current density can be reduced the most effectively by the first grain boundary. (C) 1998 Elsevier Science Ltd. All rights reserved.