Virtually doped SiGe tunnel FET for enhanced sensitivity in biosensing applications

In this work, a novel tunnel FET device architecture based on the concept of charge plasma for biosensing applications has been proposed and the sensing performance has been evaluated by comparing it to a conventionally doped double gate (DG) TFET. The use of a low bandgap material in the source region facilitates the increase in On current of TFETs. The device sensitivity is dependent on dielectric constant as well as charge density of biomolecules. Three different sensing metrics, △VTh/VTh, gm/Ids, SIds have been used to evaluate and compare the performance of biosensors. It is observed that the drain current sensitivity (SIds) and threshold voltage sensitivity △VTh/VTh is ∼1.9 times and ∼1.67 times more in CP-TFET than conventional DG-TFET respectively. The biosensor sensitivity is more dependent on the location of biomolecules within the cavity rather than the fill in factor as found by orientation analysis. The sensitivity metric gm/Ids is 28% higher in CP-TFET than conventional TFET when the biomolecules are confined near the source-channel tunneling junction.