Design, Investigation, and Sensitivity Analysis of a Biosensor Based on an Optimized Electrostatically Doped Nanotube TFET

This paper proposes an electrostatically doped nanotube TFET for biosensor (Bio-NT-TFET) application. The device design and sensitivity for bio-sensing applications are analyzed. An electrostatic doping technique is used to creating the p-type source region. Source voltage of −1.2 V (V_S = −1.2 V) is used for the electrostatically doped Bio-NT-TFET. For the design of the Bio-NT-TFET, device specifications including hole/electron carrier concentration, electric field, potential, and electron nonlocal band-to-band tunneling (BTBT) rate are investigated for K = 8. Analog parameters including ON current, drain current, OFF current, I_ON/I_OFF current ratio, subthreshold slope, threshold voltage, and the average subthreshold slope are discussed for K = 8. The Bio-NT-TFET source voltage (V_S) is found to vary from −0.2 V to −1.2 V, and the gate voltage (V_GS) varies from 0.2 V to 1 V. The variation in dielectric constant K (1, 2.1, 3.57, 8, 12, and 20) is also discussed. For bio-sensing applications, a cavity is introduced between the source region and the core source electrode region. K is defined as the dielectric constant of the material. For investigating the Bio-NT-TFET, biomolecules with different dielectric constant values (K), i.e., streptavidin (K = 2.1), (3-aminopropyl)triethoxysilane (K = 3.57), and protein (K = 8), are analyzed. To determine the bio-sensing capability, the cavity is filled with biomolecules at various fill rates: 100%, 75%, 50%, and 25% biomolecules, and no biomolecules (empty). To analyze the proposed Bio-NT-TFET, both positive biomolecules (+BM) and negative biomolecules (−BM) are taken into consideration. To analyze the efficiency of the Bio-NT-TFET, the ON current (I_ON), I_ON/I_OFF current ratio (I_ON/I_OFF), the effect of charged biomolecules (+BM/−BM), parametric analysis, and sensitivity are taken into consideration.