Dielectric modulated GaAs1− x Sb X FinFET as a label-free biosensor: device proposal and investigation

Abstract

In this paper, we propose and investigate a dielectric modulated (DM) GaAs1−x Sb x FinFET as a label-free biosensor. Raised source drain (RSD) architecture is employed in the proposed structure, resulting in a large surface to volume ratio, which provides more living space to the biomolecules. GaAs1−x Sb x is used as a channel material, which bestows higher carrier mobility and consequently offers better sensitivity than previously reported FET-based biosensors. In our proposed RSD GaAs1−x Sb x FinFET, we have embedded a nanogap (∼5.5 nm thickness) cavity between the gate and the channel region at which biomolecules can reside in a dry environment. The presence of biomolecules (charged or neutral) in the embedded nanogap cavity of a DM biosensor could be identified by the change in various electrical parameters such as ON–OFF current ratio (CR), threshold voltage (V th), transconductance, and intrinsic gain, etc, with the change in dielectric constant (K) of the cavity region. We found the maximum sensitivity corresponding to K = 12 is 48.91% and 26.31% for CR and V th, respectively. The governing physics to observe the substantial changes due to the velocity overshoot, capacitive coupling, and DIBL is thoroughly explained. The analysis of how one cavity of the proposed biosensor works at a time is also investigated. In our work, we have also identified the impact of biomolecules which carry charges by including trap models in numerical TCAD simulations.