Simulation Based Analysis of Silicon Layer Configuration under Biased and Unbiased Gate Conditions in High-k HfO₂ Triple-Gate Vertical TFET Biosensor

This paper focuses on the enhancement of Tunnel Field-Effect Transistors (TFETs) by focusing on critical performance factors such as on-current (I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</inf>), off-current (I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</inf>), and subthreshold swing (SS). Unlike traditional FETs, which rely on thermal carrier movement over an energy barrier, TFETs utilize quantum tunnelling at the source-channel junction. We designed a high-k HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Triple Gate Dielectric Modulated Vertically TFET-based biosensor (TG-DM-VTFET) for the detection of biomolecules and simulated using TCAD Silvaco tool. Our simulation results of the biosensors show significant improvements in the energy band alignment, and surface potential, which reduce the tunnelling barrier and enhance channel conduction. These improvements in band-to-band tunnelling leads to better efficiency, resulting in reduced leakage currents, improved subthreshold slopes, higher ON-state currents, and greater sensitivity, all while consuming less power. We examined five different silicon layer configurations: intrinsic, n-type, p-type, N-P configuration and P-N configuration. The n-type silicon layer configuration, both biased and unbiased, exhibited the lowest subthreshold swing and the highest I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</inf>/I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</inf> ratio, indicating more efficient current conduction at lower thresholds, which aligns well with the improvements noted in related works. In this paper, a comparative analysis of our findings with literature papers was also made. Furthermore, the use of high-k HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> dielectrics and the triple-gate structure enhance sensitivity, positioning our high-k HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> TG-DM-VTFET-based biosensor as a viable option for advanced biosensing applications.