Enhanced sensitivity of double gate junctionless transistor architecture for biosensing applications

Dielectric Modulated Nanotube Tunnel Field-Effect Transistor with Core-Shell Cavity as a Label-Free Biosensor: Proposal and Analysis

Dielectric Modulated Field-Effect Transistors (DMFETs) have emerged as promising candidates for label-free bioanalyte detection. However, the inherent short-channel effects in conventional DMFETs increase their static power dissipation significantly and limit their scalability and sensitivity. Therefore, FETs based on alternate conduction mechanism such as tunneling (TFETs), which are immune to the short-channel effects, appear to be a lucrative alternative to the MOSFETs for biosensing application. In this work, we propose a novel Dual Cavity Dielectric Modulated Nanotube Tunnel FET (DCDM NTTFET)-based label-free biosensor consisting of a Ge source and nanocavities within the core as well as a shell gate stack, which not only outperforms the conventional MOSFET and advanced nanowire (NW) TFET-based biosensors in terms of energy-efficiency and scalability but also exhibits a significantly high drain current sensitivity (SION = 2.9 × 108) and a threshold voltage sensitivity (SVth = 0.85), and a considerably high selectivity of more than 6 orders of magnitude. We also perform a comprehensive design space exploration for the proposed DCDM NTTFET and provide necessary design guidelines to further improve its performance considering the practical artifacts such as steric hindrance.

Gate-all-around junctionless FET based label-free dielectric/charge modulation detection of SARS-CoV-2 virus

The recent corona outbreak has necessitated the development of a label-free, highly sensitive, fast, accurate, and cost-effective biosensor for the detection of SARS-CoV-2 virus. This study records the label-free electrical detection of the SARS-CoV-2 virus using the gate-all-around junctionless field effect transistor (GAA-JLFET) that detects the virus because of the electrical properties (dielectric constant and charge) of spike protein, envelope protein, and virus DNA, for a highly sensitive and real-time bio-sensor. GAA-JLFETs are suitable for this application because of their highest gate controllability, potential vertical stacking, current industry trend compatibility, inherent ease of fabrication, and higher sensitivity. The SARS-CoV-2 virus is first immobilized in the etched nano-cavity embedded beneath the gate electrode, which is then used to detect it. The SARS-CoV-2 virus detection has been calibrated based on the change in system electrical properties after virus immobilization. For effective virus detection, the work takes into account both the dielectric property of S protein and the charge of DNA at the same time. The sensitivity has been calculated using ΔV _TH, ΔI _ON, Δg _m, and ΔSS. The simulation analysis also shows a simpler recovery mechanism in this case.

Sensitivity Enhancement of Dual Gate FET Based Biosensor Using Modulated Dielectric for Covid Detection

This paper presents a dual gate dielectric modulated FET (DGDMFET) biosensor with enhanced sensitivity for covid detection. In earlier literature, the biosensors are operated using the surface interaction with the virus biomolecules that are reflected through a channel or gate. The downside of these types of sensors has limited sensitivity. In this paper, we have considered that the change in the dielectric constant due to virus proteins results in a significant shift in the threshold voltage of FET. Enhancement of sensitivity is done by using the novel dual metal gate arrangement with different work functions (higher at the source end and lower at the drain end) and the chromic oxide (Cr₂O₃) layer, which is carved out vertically to form nanogap. At the same time, interface charge density is maintained nearly equal to 1.0 × 10¹¹ cm⁻² at the Si-SiO₂ layer. To demonstrate the proposed biosensor, electrical parameters (electron concentration, surface potential, energy band distribution, and electric field) and the absolute percentage sensitivity of threshold voltage, subthreshold slope, ON current, and transconductance are evaluated and compared with related literature. The ATLAS device simulator is used for the simulation of the proposed device.

Specific and label-free immunosensing of protein-protein interactions with silicon-based immunoFETs

The importance of specific and label-free detection of proteins via antigen-antibody interactions for the development of point-of-care testing devices has greatly influenced the search for a more accessible, sensitive, low cost and robust sensors. The vision of silicon field-effect transistor (FET)-based sensors has been an attractive venue for addressing the challenge as it potentially offers a natural path to incorporate sensors with the existing mature Complementary Metal Oxide Semiconductor (CMOS) industry; this provides a stable and reliable technology, low cost for potential disposable devices, the potential for extreme minituarization, low electronic noise levels, etc. In the current review we focus on silicon-based immunological FET (ImmunoFET) for specific and label-free sensing of proteins through antigen-antibody interactions that can potentially be incorporated into the CMOS industry; hence, immunoFETs based on nano devices (nanowire, nanobelts, carbon nanotube, etc.) are not treated here. The first part of the review provides an overview of immunoFET principles of operation and challenges involved with the realization of such devices (i.e. e.g. Debye length, surface functionalization, noise, etc.). In the second part we provide an overview of the state-of-the-art silicon-based immunoFET structures and novelty, principles of operation and sensing performance reported to date.

Nanowire Field-Effect Transistor Sensors

Sensitive and quantitative analysis of proteins and other biochemical species are central to disease diagnosis, drug screening and proteomic studies. Research advances exploiting SiNWs configured as FETs for biomolecule analysis have emerged as one of the most promising and powerful platforms for label-free, real-time, and sensitive electrical detection of proteins as well as many other biological species. In this chapter, we first briefly introduce the fundamental principle for semiconductor NW-FET sensors. Representative examples of semiconductor NW sensors are then summarized for sensitive chemical and biomolecule detection, including proteins, nucleic acids, viruses and small molecules. In addition, this chapter discusses several electrical and surface functionalization methods for enhancing the sensitivity of semiconductor NW sensors.

Nano-Bioelectronics

Nano-bioelectronics represents a rapidly expanding interdisciplinary field that combines nanomaterials with biology and electronics and, in so doing, offers the potential to overcome existing challenges in bioelectronics. In particular, shrinking electronic transducer dimensions to the nanoscale and making their properties appear more biological can yield significant improvements in the sensitivity and biocompatibility and thereby open up opportunities in fundamental biology and healthcare. This review emphasizes recent advances in nano-bioelectronics enabled with semiconductor nanostructures, including silicon nanowires, carbon nanotubes, and graphene. First, the synthesis and electrical properties of these nanomaterials are discussed in the context of bioelectronics. Second, affinity-based nano-bioelectronic sensors for highly sensitive analysis of biomolecules are reviewed. In these studies, semiconductor nanostructures as transistor-based biosensors are discussed from fundamental device behavior through sensing applications and future challenges. Third, the complex interface between nanoelectronics and living biological systems, from single cells to live animals, is reviewed. This discussion focuses on representative advances in electrophysiology enabled using semiconductor nanostructures and their nanoelectronic devices for cellular measurements through emerging work where arrays of nanoelectronic devices are incorporated within three-dimensional cell networks that define synthetic and natural tissues. Last, some challenges and exciting future opportunities are discussed.

Performance assessment of dual material gate dielectric modulated nanowire junctionless MOSFET for ultrasensitive detection of biomolecules

In this paper, the potential capability of a novel dielectric modulated dual material gate nanowire junctionless MOSFET as a promising biosensor is demonstrated.