In this work, the interactions and subsequent optical transductions of phenylalanine (PHE) and tyrosine (TYR) amino acids on tungsten diselenide (WSe2) nanoflakes are systematically investigated using a complementary approach involving density functional theory (DFT) based ab initio calculation and experimental characterization. The WSe2 nanoflakes are synthesized using a low-cost hydrothermal method and are subsequently characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HRSEM). The strength and efficacy of PHE and TYR interactions at different molecular conformations (namely, C1, C2, and C3) with WSe2 are theoretically quantified using binding energy and charge transfer with energy band gap modulation, respectively. Next, the major theoretical predictions were finally confirmed experimentally after examining the UV–visible spectroscopy and NMR data. The interaction mechanism was also confirmed experimentally through FT-IR and EPR studies with varying WSe2 concentrations in the solution. The key findings reveal that the presence of selenium (Se) vacancy in as-synthesized WSe2 acts as a favorable molecular interaction site for both PHE and TYR, manifested in the notable improvement in binding energies, i.e., −0.59 eV to −0.70 eV for PHE and −0.82 eV to −0.95 eV for TYR. For both PHE and TYR, the physiosorbed amino acids show a moderate (0.01 to 0.04 e–) charge transfer for pristine and Se-vacant WSe2, wherein an acceptor type charge transfer for PHE and donor type charge transfer for TYR are observed in the molecular conformations representing their respective strongest interactions with Se-vacant WSe2. The results suggest that TYR and PHE are also appealing choices for use in environmental monitoring, food safety applications, and medical diagnostics due to their high sensitivity, selectivity, and miniaturization potential. Finally, the study opens pathways for complementary investigation of other similar amino acids on other transition metal dichalcogenides (TMDs), which can also be investigated as sensor materials, and a more robust sensing mechanism can be developed for utilizing similar potential molecules for large-scale sensor development.
This paper presents a novel design scheme to reduce the short channel effects effectively in deep sub-micron MOSFET design. This scheme shows excellent improvement in the off-state current and proves to be very effective in controlling channel length modulation in nano-scale device design. This paper also proposes a subsequent theory to explain the effect of the design scheme on device characteristics supported by a through simulation study.
Abstract In this work, for the first time, the catalytic metal gate (CMG) based nanosheet Field Effect Transistor (NSFET) and nanosheet Tunnel Field Effect Transistor (NSTFET) are proposed for nano‐scale device dimensions, and the different design aspects of catalytic metal gate (CMG)‐based transduction for Hydrogen (H 2 ) sensing are extensively investigated using numerical device simulation. The influence of applied biasing conditions and structural parameter specifications on the sensing performance of CMG‐NSFET and CMG‐NSTFET are methodically analyzed from device electrostatics and carrier transport mechanisms. Furthermore, the relative maximum sensitivity variations with H 2 ‐partial pressure, ambient temperature, and the presence of ambient Oxygen are comprehensively studied. The study reveals that compared to CMG‐NSFET, the CMG‐NSTFET demonstrates a high immunity against bias and doping variations, with a notably higher (> 50%) sensitivity within low H 2 partial pressures (10 −15 – 10 −10 Torr). Next, the sensing performance of CMG‐NSTFET is systematically optimized through a band‐gap and gate‐stack engineering approach, leading to a 180% to 650% sensitivity improvement from lower (10 −15 Torr) to higher (10 −5 Torr) range of H 2 partial pressure. Finally, the performance of optimized CMG‐NSFET and CMG‐NSTFET are extensively benchmarked against other reported nanostructured CMG‐FET and TFET‐based H 2 gas sensors, exhibiting a notably higher sensitivity in the proposed sensors.
In this work, a Short Gate Insulator Less Dielectrically Modulated Tunneling Field Effect Transistor (SGIL-DMTFET) structure is explored in details for bio-sensing applications by using extensive device-level simulation. A comprehensive physical understanding is developed on the gate-engineering technique of DMTFET for bio-molecule conjugation. Such understanding is then successfully extended to analyze the working principle of SGIL architecture and its inherently superior current sensitivity over the conventional DMTFET. A comparative performance study has been performed on the basis of biasing conditions and the relevant biasing range of operations is indicated for both the DMTFETs. Further, the comparative sensing performance of DMTFETs is associated with their relative nature of threshold voltage shift (for conjugation) and sub-threshold swing. Finally, the cavity length and channel thickness are identified as the fundamental device parameters for optimizing sensitivity for both the biosensors.
In this work, an inverter-based biomolecule detection strategy has been introduced for dielectrically modulated biosensing applications that show a clear output logic-state transition after conjugation. Subsequently, a bioring-oscillator has been realized based on such bioinverters, where biomolecules can be detected from the oscillation frequency amplification with conjugation. To optimize the detection efficiency, a dielectrically modulated fringing field effect transistor based transducer has been incorporated as the pull-up/pull-down elements of such bioinverter. The underlying physics of such structure has been investigated and subsequent electrical response has been estimated for various biomolecule sample specifications. This work explores different bioinverter configurations, and subsequently the suitable choice of bioinverter has been indicated for charged and charge-neutral biomolecule detection. Similar studies have been performed for bioring oscillator, and the roles of supply voltage scaling and oscillator stage enhancement have been investigated in this context.
Owing to their augmented electrical, optical, mechanical, chemical, and thermal properties, nanomaterials have proven to be superior to their bulk counterpart in almost every aspect of consumer applications. For the past two decades, a great deal of scientific study is going on exploring these materials in order to take advantage of these nanomaterials in various fields of research. By changing the type of orbital hybridization, carbon can take the form of various nano-allotropes. Since all nano-allotropes of carbon have unusual physical and chemical characteristics, they are widely used in many different applications, particularly in the electronics industry. Fullerenes, graphene, and carbon nanotubes/nanoribbons are some of the most common examples of three-, two-, and one-dimensional carbon nano-allotropes. These carbon-based materials that have displayed such inherent properties can be easily exploited in the making of cutting-edge technology applications. The aforementioned distinctive qualities suggest that carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) may be used as replacement materials for future nano-scale interconnects, thus improving electrical performance and removing electro-migration reliability issues that have been afflicting Cu-based nano-scale interconnects for a long time. In this chapter, the distinctive characteristics of various nanomaterials are highlighted, along with their current and potential interconnect applications in the future.
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