Analytical modeling of gate-all-around junctionless transistor based biosensors for detection of neutral biomolecule species

Abstract

In recent times, FET-based sensors have been widely used in industrial and domestic applications due to their low cost and high sensitivity. In this paper, a nanogap-embedded gate-all-around junctionless transistor (GAA JLT) is proposed for label-free electrochemical detection of neutral biomolecule species such as Uricase, Protein, ChOx, APTES and Streptavidin. Shifts in subthreshold current, threshold voltage and capacitance are used to predict the response of the sensor. Impact of cavity width, cavity length, and gate length on the sensitivity of a junctionless transistor has also been investigated in detail. An analytical model has been developed for a GAA JLT-based biosensor. The results are compared with an inversion mode transistor-based biosensor using TCAD numerical simulation. The GAA JLT shows very high sensitivity due to the gate all around structure and bulk conduction mechanism.

Appendix

Coefficients of Eqs. (20)–(23) are given as;

$$\begin{aligned} \eta _{1}= & {} \frac{2}{a^{2}\left[ {J_1^2 \left( K \right) +J_0^2 \left( K \right) } \right] } \end{aligned}$$

(A1)

$$\begin{aligned} \eta _{2}= & {} \frac{a^{2}\eta _1 l_\mathrm{SD}^2 \xi J_1 (K)}{2K} \end{aligned}$$

(A2)

$$\begin{aligned} \tau _1= & {} \frac{a^{2}\eta _1 J_1 \left( K \right) }{K}\left( {V_\mathrm{R} -V_\mathrm{gs} +V_\mathrm{fb1} -\frac{qaN_\mathrm{D} }{2C_\mathrm{GAA1}}} \right) \nonumber \\&-\frac{a^{4}\eta _1 \xi J_2 \left( K \right) }{2K^{2}} \end{aligned}$$

(A3)

$$\begin{aligned} \tau _2= & {} \frac{a^{3}\eta _1 \xi J_1 \left( K \right) }{K^{2}} \end{aligned}$$

(A4)

$$\begin{aligned} \tau _4= & {} \frac{a^{2}\eta _1 J_1 \left( K \right) }{K}\left( {V_\mathrm{R}+V_\mathrm{ds}-V_\mathrm{gs} +V_\mathrm{fb2}-\frac{qaN_\mathrm{D}}{2C_\mathrm{GAA2}}} \right) \nonumber \\&-\frac{a^{4} \eta _{1} \xi J_2 \left( K \right) }{2K^{2}}. \end{aligned}$$

(A5)