Split Gate Bulk-Planar Junctionless FET-Based Biosensor for Label-Free Detection of Biomolecules

In this article, for the first time, we demonstrate the fabrication of low-cost split gate bulk planar junctionless field-effect transistor (SG-BPJLFET) for biosensing applications. In the fabrication process, the junctionless concept has been incorporated to reduce the thermal budget, random dopant fluctuations, and the fabrication complexities of the device. The measured transfer characteristics of the fabricated SG-BPJLFET show improved <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{{ON}}$ </tex-math></inline-formula>/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{{OFF}}$ </tex-math></inline-formula> ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{{7}}$ </tex-math></inline-formula> with the calculated mobility of 9.72 cm2/V<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>s and the charge carrier density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 \times 10^{{18}}$ </tex-math></inline-formula> cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{3}}$ </tex-math></inline-formula>. For the fabricated device, Debye’s length is found to be 6.45 nm, which can be used for the detection of protein complexes (such as streptavidin–biotin) by using <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.01 \; \times $ </tex-math></inline-formula> phosphate buffer solution (PBS) in solution. The fabricated device is further simulated for the detection of biomolecules such as streptavidin and biotin. From the simulated results, it has been observed that the device has the capability to be used as a biosensor for detection of various protein complexes with higher sensitivity and selectivity.