INVESTIGATION OF HOT-CARRIER TRANSPORT IN SILICON PERMEABLE BASE TRANSISTORS

The effects of variations in the source to drain distance have been in vestigated for several highly doped Permeable Base Transistor (PET) st ructures. A detailed study of the hot electron transport in these stru ctures is presented using a 2-D self-consistent full hand Monte Carlo (MC) simulation program, The PET structures considered are the overgro wn, etched source and etched Brain PET, Finally we have simulated a st ructure where both the source and the drain have been etched, All stru ctures have a high doping level in the channel (10(17) cm(-3)) and are operating under a gate biasing far from the threshold voltage, The et ched structure shows a larger increase in the unity current gain frequ ency (f(I)) than the overgrown structure as the source to drain distan ce decreases, By optimizing the source to drain distance of the etched source PBT, the f(T) can be increased by a factor of two, Our Monte C arlo result has been compared with an ordinary drift-diffusion (DD) mo del and a more advanced energy transport (ET) model, The difference be tween the MC anti DD model is largest for the etched structures, while it is less significant for the overgrown, structure. However, all str uctures considered in this work, long and short channel devices, show a larger dc current level in the MC model, This is related to the larg e electric field and high carrier temperature near the gate depletion region.