GaSb/GaAs Type-II Heterojunction TFET on SELBOX Substrate for Dielectric Modulated Label-Free Biosensing Application
Ashish Kumar Singh, Manas Ranjan Tripathy, Kamalaksha Baral, Satyabrata Jit
Abstract
A novel GaSb/GaAs type-II heterojunction TFET on SELBOX substrate (HJ-STFET)-based dielectric-modulated ultrasensitive label-free biosensor has been demonstrated in this article. The SELBOX substrate has been used in the proposed TFET-based sensor to reduce the lattice heat and improve the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\mathrm {ON}}/{I}_{{\mathrm {OFF}}}$ </tex-math></inline-formula> ratio. Cavities in the gate oxide of the TFET are created to form dual-cavity (DC) HJ-STFET structure. These cavities contain the biomolecules to be sensed through the principle of gate-dielectric modulation. To validate the results, the analytical modeling of surface potential has been compared to simulated outcomes for different dielectric constant values of biomolecules. The threshold voltage sensitivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{VT}$ </tex-math></inline-formula> ) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\mathrm{ON}}/{I}_{\mathrm{OFF}}$ </tex-math></inline-formula> sensitivity parameters of the proposed DC-HJ-STFET structure have been thoroughly investigated considering different biomolecules. The proposed DC-HJ-TFET structure is shown to have a higher current sensitivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 6.67\times10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> ) and threshold voltage sensitivity (0.37 V) values over some recently reported TFET-based biosensors. Finally, we have verified the drain and back gate biasing, as well as linearity fit verification, on the proposed biosensor’s performance.