Impact of Work function Engineering in Charge Plasma Based Bipolar Devices

Abstract In this paper, we have explored and justified the reason behind the degradation in the cutoff frequency of the bipolar transistors evolved from the charge plasma concept. It has been observed that if the work function difference present between the emitter metal contact and silicon is greater than or equal to 0.68 eV ( ϕ m - ϕ SI = 4.05 eV - 4.73 eV), it results in increment in the base width which is the inverse of the cutoff frequency. On top of this, two dimensional TCAD simulation of the different bipolar devices also demonstrate the same base width widening effect into the intrinsic region which is present between the base region and collector region. Apart from this, if this difference is exactly equal to 0.5 eV ( ϕ m - ϕ SI = 4.23 eV - 4.73 eV) then the base width widening effect can be completely eliminated from the bipolar devices base on the charge plasma.