Silicon Nanowire Field-effect Transistors Research Articles

A proposal and simulation analysis for a novel architecture of gate-all-around polycrystalline silicon nanowire field effect transistor

A proposal for a novel gate-all-around (GAA) polycrystalline silicon nanowire (poly-SiNW) field effect transistor (FET) is presented and discussed in this paper. The device architecture is based on the realization of poly-SiNW in a V-shaped cavity obtained by tetra methyl ammonium hydroxide (TMAH) etch of monocrystalline silicon (100). The device’s behavior is simulated using Silvaco commercial software, including the density of states (DOS) model described by the double exponential distribution of acceptor trap density within the gap. The electric field, potential, and free electron concentration are analyzed in different nanowire regions to investigate the device's performance. The results show good performance despite the high density of deep states in poly-SiNW. This can be explained by the strong electric field caused by the corner effect in the nanowire, which favors the ionization of the acceptor traps and increases the free electron concentration.

Aptasensors based on silicon nanowire field-effect transistors for electrical detection of thrombin

Arrays of silicon nanowire field-effect transistors (Si NWFETs) were built to detect thrombin (a model biomarker) electrically. The Si NWFETs were created using a conventional top-down CMOS process, allowing them to be co-integrated with CMOS readout circuits in the future. EHTES organosilane was then used to graft aptamer probes onto the HfO2 gate oxide of Si nanowires. We investigated the influence of aptamer grafting and thrombin recognition on the electrical transfer capabilities of Si NWFET aptasensors in details. Our technique was evaluated on a significant number of Si NWFETs, including two distinct chips with 30 aptasensors apiece. According to the findings, aptamer grafting increased the threshold voltage by a positive range of +28.8 mV to +87.7 mV, depending on the aptasensor employed. Thrombin identification, on the other hand, resulted in a negative shift of the threshold voltage between −26.6 and − 23.8 mV. These opposing voltage shifts coincide with the aptamer probes' and thrombin molecules' electric charges, respectively. These findings provide unique demonstration of Si NWFETs manufactured utilizing typical top-down CMOS processing methods, allowing these devices to be used in various biomedical and biosensing applications.

Detection of DNA nucleotides via silicon nanowire field-effect transistor sensors with a nanogap: Semi-empirical modeling

Silicon Nanowire field-effect transistors (SiNW FETs) have become very popular as they enable enhanced sensing capabilities, such as high-sensitivity, selectivity, and real-time detection. This research aimed at studying Silicon Nanowire Field effect transistor with a nanogap that is capable enough to create unique electronic signatures representing individual DNA nucleotides (Adenosine, Guanosine, Thymidine & Cytidine). In this work, two different transistor systems- back-gated SiNW FET and Gate All Around SiNW FET - were studied for the purpose of DNA nucleotide detection. Electronic transport properties such as current, transmission spectrum, and density of states were studied for both types of transistors. In the presence of Adenosine, the Gate All Around sensor reading was significantly enhanced from 0.07 nanoamperes to 3 nanoamperes, greatly improving the sensor's ability to differentiate between nucleotides.The study's findings indicate that the GAA SiNW FET outperforms the back-gated SiNW FET in terms of sensitivity when detecting DNA nucleotides. To examine the mechanics behind this process, non-equilibrium Green's function integrated with a semi-empirical model was utilized. The results showed that each type of DNA nucleotide could be detected by the designed SiNW FET sensor.

Visualizing single-molecule conformational transition and binding dynamics of intrinsically disordered proteins

Intrinsically disordered proteins (IDPs) play crucial roles in cellular processes and hold promise as drug targets. However, the dynamic nature of IDPs remains poorly understood. Here, we construct a single-molecule electrical nanocircuit based on silicon nanowire field-effect transistors (SiNW-FETs) and functionalize it with an individual disordered c-Myc bHLH-LZ domain to enable label-free, in situ, and long-term measurements at the single-molecule level. We use the device to study c-Myc interaction with Max and/or small molecule inhibitors. We observe the self-folding/unfolding process of c-Myc and reveal its interaction mechanism with Max and inhibitors through ultrasensitive real-time monitoring. We capture a relatively stable encounter intermediate ensemble of c-Myc during its transition from the unbound state to the fully folded state. The c-Myc/Max and c-Myc/inhibitor dissociation constants derived are consistent with other ensemble experiments. These proof-of-concept results provide an understanding of the IDP-binding/folding mechanism and represent a promising nanotechnology for IDP conformation/interaction studies and drug discovery.

Application of Silicon Nanowire Field Effect Transistor (SiNW-FET) Biosensor with High Sensitivity.

As a new type of one-dimensional semiconductor nanometer material, silicon nanowires (SiNWs) possess good application prospects in the field of biomedical sensing. SiNWs have excellent electronic properties for improving the detection sensitivity of biosensors. The combination of SiNWs and field effect transistors (FETs) formed one special biosensor with high sensitivity and target selectivity in real-time and label-free. Recently, SiNW-FETs have received more attention in fields of biomedical detection. Here, we give a critical review of the progress of SiNW-FETs, in particular, about the reversible surface modification methods. Moreover, we summarized the applications of SiNW-FETs in DNA, protein, and microbial detection. We also discuss the related working principle and technical approaches. Our review provides an extensive discussion for studying the challenges in the future development of SiNW-FETs.

Comparing surface modification methods for silicon nanowire field-effect transistor biosensors for diagnosis applications: A case study of cardiac troponin I

This study is a debut of a side-by-side comparison of different methods to modify the surfaces of the silica-based substrates for biosensor fabrication. The fabricated biosensors are assessed for the quantification of cardiac troponin I (cTnI), a biomarker of acute myocardial infarction, at ultralow concentrations and small increment resolution in human serum. To accomplish this, silica samples and silicon nanowire field-effect transistor (SiNWFET) channels were modified with (3-aminopropyl)triethoxysilane, 1-(3-aminopropyl)silatrane, and the mixed self-assembly monolayer of silane-polyethylene glycol (silane-PEG, constituting of silane-PEG-NH2 and silane-PEG-OH at the ratio of NH2:OH = 1:10). Afterwards, they were treated with glutaraldehyde to immobilize aptamer probes for cTnI aptasensor detection. Thereafter, the modified-silica samples were investigated for surface roughness and antifouling capability, whereas the SiNWFET aptasensors were employed to determine cTnI. Empirical data revealed that only the silane-PEG-modified samples provided a superior surface for probe immobilization and high antifouling capability for the PEG-SiNWFET aptasensors to determine cTnI at ultralow levels with high resolution in human serum. Therefore, surface modification with silane-PEG provided an option for the challenge of precise quantification of cTnI, as well as of other protein biomarkers, at ultralow levels in bio-samples using the FET-based biosensors.

Ultrasensitive Silicon Nanowire Biosensor with Modulated Threshold Voltages and Ultra-Small Diameter for Early Kidney Failure Biomarker Cystatin C.

Acute kidney injury (AKI) is a frequently occurring severe disease with high mortality. Cystatin C (Cys-C), as a biomarker of early kidney failure, can be used to detect and prevent acute renal injury. In this paper, a biosensor based on a silicon nanowire field-effect transistor (SiNW FET) was studied for the quantitative detection of Cys-C. Based on the spacer image transfer (SIT) processes and channel doping optimization for higher sensitivity, a wafer-scale, highly controllable SiNW FET was designed and fabricated with a 13.5 nm SiNW. In order to improve the specificity, Cys-C antibodies were modified on the oxide layer of the SiNW surface by oxygen plasma treatment and silanization. Furthermore, a polydimethylsiloxane (PDMS) microchannel was involved in improving the effectiveness and stability of detection. The experimental results show that the SiNW FET sensors realize the lower limit of detection (LOD) of 0.25 ag/mL and have a good linear correlation in the range of Cys-C concentration from 1 ag/mL to 10 pg/mL, exhibiting its great potential in the future real-time application.

High Performance of Liquid‐Gated Silicon Nanowire FETs Covered with Ultrathin Layers of Diamond‐Like Tetrahedral Amorphous Carbon

Label‐free, low‐noise, and ultrahigh‐sensitive biosensors based on liquid‐gated silicon (Si) nanowire (NW) field‐effect transistors (FETs) have recently emerged as promising diagnostic tools that can be used for healthcare monitoring and point‐of‐care applications. However, the sensing capabilities and performance of such devices still critically depend on several factors, including the quality and intrinsic properties of the materials used. In particular, the important role of determining device performance is assigned to the gate insulator layer, which acts as a sensing surface in such NW‐based biosensors and still requires optimization. Herein, several advanced multilayer structures: Si NW/SiO2/diamond‐like carbon FETs, are investigated. The high quality of the diamond‐like carbon layer obtained by low‐temperature physical vapor deposition is confirmed by X‐ray photoelectron spectroscopy and Raman spectroscopy studies. Current–voltage and noise spectroscopy reflect the high‐quality transport properties in these structures.

Polycrystalline silicon nanowire FET performance depending on density of states

Polycrystalline silicon nanowire FET performance depending on density of states

Digital-to-analog converter implementation based on silicon nanowire FET

Digital-to-analog converter implementation based on silicon nanowire FET

Alanine aminotransferase assay biosensor platform using silicon nanowire field effect transistors

Frequent monitoring of serum alanine aminotransferase (ALT) activity is essential to prevent drug-induced liver injury (DILI). Current ALT assays are restricted to centralized clinical laboratories, making frequent patient monitoring logistically difficult. To address this, we demonstrated the capability of commercial foundry manufactured silicon nanowire field effect transistor (SiNW-FET) biosensors in a form factor that enables frequent near-patient monitoring. Here, we designed an ALT assay, by coupling the ALT-catalyzed production of pyruvate to the reduction of ferricyanide, enabling both spectrophotometric and electrical measurement of ALT activity. The two methods yield comparable ALT activity detection across a dynamic range wide enough to monitor patients at risk for DILI. This study demonstrates kinetic activity measurement of an endogenous enzyme using uncoupled SiNW-FETs, and commercial manufacturing of SiNW-FET sensor arrays for use in a portable biosensor platform.

Gate Engineered Silicon Nanowire FET with Coaxial Inner Gate for Enhanced Performance

Gate Engineered Silicon Nanowire FET with Coaxial Inner Gate for Enhanced Performance

The insight and evaluation of ultra-scaled sub-1 nm gate length transistors

There is a great attention of scaling down transistor based on 2D materials. Although gate-all-around (GAA) structure based on silicon has been simulated, the GAA structure combined with 2D materials do not have a well understanding. Moreover, the recent proposed edge graphene gated transistor also needs deeper analysis. Here, edge graphene gated 2D-FETs are further investigated and optimized by employing semi-classical numerical method. The physical dimensions can be optimized to obtain performance improvement, and some possible schemes are proposed. We demonstrate fair quantitative comparison for our proposed 0.34 nm graphene edge gated MoS2 and GAA graphene gated silicon nanowire device structure. It is found that the edge graphene gated MoS2 FET can achieve superior short channel performance compared to GAA graphene gated silicon nanowire and traditional GAA silicon nanowire FET, due to the generic nature of 2D TMDs, which possess direct narrow bandgap, low dielectric constant and atomic thickness. We have figured out that the 0.34 nm edge graphene gated MoS2 FET has even better subthreshold swing than the Si-GAA and Graphene-GAA, which shows promising prospect as next generation electronics.

Polyethylene Glycol Functionalized Silicon Nanowire Field-Effect Transistor Biosensor for Glucose Detection.

Accurate monitoring of blood glucose levels is crucial for the diagnosis of diabetes patients. In this paper, we proposed a simple "mixed-catalyzer layer" modified silicon nanowire field-effect transistor biosensor that enabled direct detection of glucose with low-charge in high ionic strength solutions. A stable screening system was established to overcome Debye screening effect by forming a porous biopolymer layer with polyethylene glycol (PEG) modified on the surface of SiNW. The experimental results show that when the optimal ratio (APTMS:silane-PEG = 2:1) modified the surface of silicon nanowires, glucose oxidase can detect glucose in the concentration range of 10 nM to 10 mM. The sensitivity of the biosensor is calculated to be 0.47 μAcm-2mM-1, its fast response time not exceeding 8 s, and the detection limit is up to 10 nM. This glucose sensor has the advantages of high sensitivity, strong specificity and fast real-time response. Therefore, it has a potential clinical application prospect in disease diagnosis.

Single-exonuclease nanocircuits reveal the RNA degradation dynamics of PNPase and demonstrate potential for RNA sequencing

The degradation process of RNA is decisive in guaranteeing high-fidelity translation of genetic information in living organisms. However, visualizing the single-base degradation process in real time and deciphering the degradation mechanism at the single-enzyme level remain formidable challenges. Here, we present a reliable in-situ single-PNPase-molecule dynamic electrical detector based on silicon nanowire field-effect transistors with ultra-high temporal resolution. These devices are capable of realizing real-time and label-free monitoring of RNA analog degradation with single-base resolution, including RNA analog binding, single-nucleotide hydrolysis, and single-base movement. We discover a binding event of the enzyme (near the active site) with the nucleoside, offering a further understanding of the RNA degradation mechanism. Relying on systematic analyses of independent reads, approximately 80% accuracy in RNA nucleoside sequencing is achieved in a single testing process. This proof-of-concept sets up a Complementary Metal Oxide Semiconductor (CMOS)-compatible playground for the development of high-throughput detection technologies toward mechanistic exploration and single-molecule sequencing.

Ultrasensitive Detection of Interleukin 6 by Using Silicon Nanowire Field-Effect Transistors.

Interleukin 6 (IL-6) has been regarded as a biomarker that can be applied as a predictor for the severity of COVID-19-infected patients. The IL-6 level also correlates well with respiratory dysfunction and mortality risk. In this work, three silanization approaches and two types of biorecognition elements were used on the silicon nanowire field-effect transistors (SiNW-FETs) to investigate and compare the sensing performance on the detection of IL-6. Experimental data revealed that the mixed-SAMs-modified silica surface could have superior surface morphology to APTES-modified and APS-modified silica surfaces. According to the data on detecting various concentrations of IL-6, the detection range of the aptamer-functionalized SiNW-FET was broader than that of the antibody-functionalized SiNW-FET. In addition, the lowest concentration of valid detection for the aptamer-functionalized SiNW-FET was 2.1 pg/mL, two orders of magnitude lower than the antibody-functionalized SiNW-FET. The detection range of the aptamer-functionalized SiNW-FET covered the concentration of IL-6, which could be used to predict fatal outcomes of COVID-19. The detection results in the buffer showed that the anti-IL-6 aptamer could produce better detection results on the SiNW-FETs, indicating its great opportunity in applications for sensing clinical samples.

Design and Performance Assessment of Graded Channel Gate-All-Around Silicon Nanowire FET for Biosensing Applications

Design and Performance Assessment of Graded Channel Gate-All-Around Silicon Nanowire FET for Biosensing Applications

A novel biosensor based on a bio-barcode for the detection of Mycobacterium tuberculosis.

Tuberculosis (TB), the second (after COVID-19) deadliest infectious killer, is a chronic infectious disease caused by infection with Mycobacterium tuberculosis (M.T.), where early diagnosis and management are the key to containing the condition. Here, we report a novel biosensor for the detection of M.T. DNA based on magnetic separation, urease catalysis and silicon nanowire field effect transistor (SiNW FET) detection. M.T. DNA is sequence-specifically captured by magnetic nanoparticles and urease-labelled silica nanoparticles simultaneously to form a sandwich complex and urea is catalyzed into ammonium carbonate by urease modified on a sandwich complex. By using SiNW FET, the detection of M.T. DNA is realized indirectly by the detection of ammonium carbonate. The limit of detection (LOD) was determined to be 78.541 fM. The specificity of the biosensor was confirmed by detecting a panel of bacterial species. The utility of the biosensor was demonstrated in real-sample analysis and the recovery study of M.T. DNA was done in the genomic DNA extracted from cultured Mycobacterium tuberculosis. The biosensor holds promise to become a rapid, sensitive and accurate method for clinical diagnosis.

Impact of high-k metal oxide as gate dielectric on the certain electrical properties of silicon nanowire field-effect transistors: A simulation study

Standard Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) are gaining prominence in low-power nanoscale applications. This is largely attributed to their proximity to physical and thermal limits, rendering them a compelling option for energy-efficient electronic devices. In this study, we hypothesized that the high-? HfO2 in a quasi-ballistic SiNW MOSFET acts as the gate dielectric. In this case, the data from the TCAD simulation and the model demonstrated exceptional agreement. The proposed model for a SiNW MOSFET with high-? HfO2 exhibits a consistently increasing drain current, albeit with a smaller magnitude compared to a quasi-ballistic device (QBD). Additionally, it shows reduced mobility and decreased transconductance when considering the combined effects of scattering and temperature. As gate voltage increases, temperatureinduced transconductance decline in SiNW MOSFETs becomes significant. Our method is suitable for modeling scattered SiNW MOSFETs with temperature effects, as TGF values are similar in the subthreshold region for both Near Ballistic and Scattered SiNW MOSFET models.

Dual-Channel Detection of Breast Cancer Biomarkers CA15-3 and CEA in Human Serum Using Dialysis-Silicon Nanowire Field Effect Transistor.

Breast cancer (BC) is the most common malignant tumors and the leading cause of cancer deaths among women. The early diagnosis and treatment of BC are effective measures that can increase survival rates and reduce mortality. Carbohydrate antigens 15-3 (CA15-3) and carcinoma embryonic antigens (CEA) have been regarded as the most two valuable tumor markers of BC. The combined detection of CA15-3 and CEA could improve the sensitivity and accuracy of early diagnosis for BC. The multi-channel double-gate silicon nanowire field effect transistor (SiNW-FET) biosensors were fabricated by using the top-down semiconductor manufacturing technology. By surface modification of the different SiNW surfaces with monoclonal CA15-3 and CEA antibodies separately, the prepared SiNW-FET was processed into biosensor for dual-channel detection of CA15-3 and CEA. The prepared SiNW-FET biosensors were proved to have high sensitivity and specificity for the dual-channel detection of CA15-3 and CEA, and the detection limit is as low as 0.1U/mL CA15-3 and 0.01 ng/mL CEA. Moreover, the SiNW-FET biosensors were able to detect CA15-3 and CEA in serum by connecting a miniature hemodialyzer. The present study reported a SiNW-FET biosensor for dual-channel detection of breast cancer biomarkers CA15-3 and CEA in serum, which has potential clinical application value for the early diagnosis and curative effect observation of BC.