A simulation study on thin SOI bipolar transistors with fully or partially depleted collector

Vertical npn BJTs on thin SOI with a partially or fully depleted collector are studied by 2-dimensional device simulations. It is found that compared to conventional bulk BJTs, the SOI BJTs have a reduced base-collector capacitance, a higher Early voltage and a higher breakdown voltage. A SOI BJT with a fully-depleted collector can achieve a higher fmax with a comparable current gain and fT.