Label Free DNA Detection Techniques Using Dielectric Modulated FET: Inversion or Tunneling?

Abstract

In this paper, a feasibility estimation of inversion and tunneling based n-type dielectric modulated transistor has been extensively carried out for label free DNA detection. The sensing ability of the devices are investigated based on shift in threshold voltage and on-current ($I_{on}$ ) with respect to change in permittivity, angle of orientation, and negative charge density of DNA biomolecules. The investigation results show that n-channel Tunneling Field Effect Transistor (TFET) has better sensing capability than n-channel Inversion Mode Field Effect Transistor (IMFET) without compromising on scaling issues. When DNA biomolecules are anchored in the nanogap region, the n-channel IMFET exhibits the shift in threshold voltage and adequate sensitivity. However, it requires a high gate bias to detect the biomolecule. In the case of n-channel TFET, steep subthreshold swing with high $I_{on}$ is observed at low gate bias. Consequently, the sensitivity of TFET is enhanced by 63% when compared with IMFET. This results show TFET devices are superior and can replace the existing IMFET with cost effectiveness. The design and comparative evaluation of the devices are carried out with 2D Silvaco TCAD.