MONTE-CARLO ANALYSIS OF VELOCITY OVERSHOOT EFFECTS IN BIPOLAR-DEVICESWITH AND WITHOUT AN I-LAYER

We investigated the impact of velocity over-shoot effect on collector signal delay of bipolar devices by using Monte Carlo simulation method . We found that insertion of an i-layer (lightly doped, intrinsic laye r) between base and collector can increase the delay, but the strength of this effect is a function of the i-layer thickness. When the i-lay er becomes thinner, the problem of increasing delay seems to disappear . This recovery of delay is realised with a mechanism which is complet ely different from that in drift-diffusion model.