Silicon Nanowires Research Articles

Fabrication and Simulation of Silicon Nanowire pH Sensor for Diabetes Mellitus Detection

Diabetes Mellitus (DM) is a disease failed to control the balance of blood sugar level due to lack of insulin thereby it effect human health. In Malaysia, there are around 3.9 millions people aged 18 years old and above have diabetes according to National Health and Morbidity Survey 2019. Silicon Nanowire is a nanostructure which has ultra-high sensitivity and non-radioactive that has potential given good performances when applied on pH sensor and biosensor. Silicon nanowire pH sensor and biosensor is an electronic sensor that investigated to improve the sensitivity and accuracy for detecting DM. This project consists of two parts, which are fabrication of silicon nanowire pH sensor and simulation of silicon nanowire biosensor as preliminary study. In fabrication, silicon nanowire of pH sensor is fabricated by conventional lithography process, reaction ion etching (RIE) and metallization to achieved the width of 100 nm silicon nanowire. The pH6, pH7, pH10 and DI water as analytes to analysis the current-voltage (I-V) characteristics of silicon nanowire pH sensor. In second part, the silicon nanowire biosensor as preliminary study is done simulation by Silvaco ATLAS devices simulator. The silicon nanowire with 30 nm in height and 20 nm in width of biosensor is designed and simulated to analyze the performance in terms of sensitivity. I-V characteristics of silicon nanowire biosensor according to different concentration of negative interface charge is determined. The negative interface charge represent as the Retinol Binding Protein 4 (RBP4) which is used to diagnose DM. The I-V characteristic based on the change in current, resistance and conductance to determine sensitivity. Lastly, the sensitivity of silicon nanowire pH sensor obtained 23.9 pS/pH while the sensitivity of simulated silicon nanowire biosensor obtained 3.91 nS/e.cm2. The results shown the more negative charge of concentration analyte attached on surface silicon nanowire has been accumulated more current flow from drain terminal to source terminal. It leads to the resistance becomes highest and obtained good sensitivity. In summary, the silicon nanowire pH sensor exhibited good performance and high sensitivity in detection pH level. The simulated silicon nanowire biosensor is capable of detecting biomolecular interactions charges to obtained high sensitive and accuracy result.

High-performance PANI sensor on silicon nanowire arrays for sub-ppb NH3 detection

For industrial production and disease diagnosis, real-time detection of low concentrations of NH3 is crucial, necessitating a gas-sensitive sensor compatible with integrated processes and exhibiting excellent performance. Herein, we employed wet etching and rapid in-situ polymerization on silicon nanowire substrates to grow polyaniline fibers, thereby fabricating NH3 gas sensors with p-p heterojunction and three-dimensional network structures. Characterization and gas sensing performance testing were conducted. The results demonstrate the outstanding NH3 detection capabilities of the sensor, providing stable responses down to concentrations as low as 1 ppb, which indicates its LOD is one to two orders of magnitude lower than current similar products. It also exhibits verified selectivity and long-term reliability. The excellent sensing performance is attributed to the high surface area from the silicon nanowire structure and efficient synergy of p-p heterojunction. Additionally, the influence of doping types of the substrates and annealing process were explored. This work serves as a reference for the design of silicon-based gas sensors with high sensitivity, low detection limits, and extended operational lifetimes, suitable for deployment in commercial integrated monitoring systems.

Gate-driven transition temperatures of electron hopping behaviors in Hubbard bands formed by dopant-induced QD array in silicon nanowire

Abstract Dopant atoms confined in silicon nanoscale channel can be ionized to form quantum dots (QDs). Several dopant atoms couple with each other forming energy bands, where the electron hopping behavior can be described by the Hubbard model. This characteristic renders dopant-induced quantum dots particularly appealing for applications in nanoelectronic and quantum devices. Herein we study the gate-driven transition temperatures of electron hopping behavior in upper and lower Hubbard bands formed by dopant-induced QD array in junctionless silicon nanowire transistors. The gate-dependent transition temperatures are calculated for three stages of electron hopping behaviors including Efros-Shklovskii Variable Range Hopping (ES-VRH), Mott Variable Range Hopping (Mott-VRH) and Nearest Neighbor Hopping (NNH). Our experimental results indicate that the ES-VRH in arrays of dopant atoms occurs in the domination of a long-range Coulomb interaction, in which the hopping distance relies on the Coulomb gap. Furthermore, the localization length of ES-VRH can be modulated by gate voltages.Those factors lead to the significant difference of transition temperatures between the upper and lower Hubbard bands. In addition, we find that the source-drain bias voltage can effectively modulate the transition temperatures between VRH and NNH by thermal activation energies under different bias voltages Vds.

Dynamics of VLS-Grown Si Nanowires: Insights from Molecular Dynamics Simulations on Facet Evolution, Twinning, Nucleation, and Impurity Dynamics

Dynamics of VLS-Grown Si Nanowires: Insights from Molecular Dynamics Simulations on Facet Evolution, Twinning, Nucleation, and Impurity Dynamics

Hyperspectral Analysis of Silicon Nanowires Manufactured Through Metal-Assisted Chemical Etching

Abstract This study used hyperspectral imaging to analyze localized near-field interactions between incident electromagnetic waves and silicon nanowire (SiNW) arrays manufactured through catalytic etching of Si wafers for different durations. The results revealed that the unetched upper surface area on Si wafers and reflection of incident light decreased with increasing etching time. A light reflection band peaking at approximately 880 nm was generated from arrays etched for more than 1 h. We used six separate hyperspectral images to analyze the wavelength-dependent spatial optical responses of the fabricated SiNW arrays. The images revealed hot spots of light reflection from unetched Si surfaces in the wavelength range of 470–750 nm and a resonant peak at 880 nm for a photonic crystal derived from a random SiNW array. Accordingly, hyperspectral imaging enables the assessment of localized optical responses of SiNW arrays, which can then be optimized to cater to various applications.

Silicon Nanowire Biosensors for Diabetes Mellitus Monitoring

The main goal of this research is the development of a label-free biosensor for the detection of diabetes mellitus (DM) using the target molecule retinol-binding protein 4 (RBP4). The enzyme-linked immunosorbent assay (ELISA) approach, currently used to detect DM, is time-consuming and difficult. As a result, label-free biosensors are being considered as an alternative. In this research, silicon nanowires (SiNWs) were selected as the transducer for this biosensor due to their low cost, real-time analysis capability, high sensitivity, and low detection limit. The SiNWs were created using conventional lithography, reactive ion etching (RIE), and physical vapor deposition (PVD), and then dripped with a gold nanoparticle solution to create gold-decorated SiNWs. The surface of the gold-decorated SiNWs was functionalized using 3-aminothiophenol and glutaraldehyde solutions before being immobilized with DM RBP4 antibodies and targets. The electrical characterization of the gold nanoparticle decorated SiNWs biosensor revealed good performance in DM detection. The pH tests confirmed that the SiNWs acted as a transducer, with current proportional to the DM RBP4 concentration. The estimated limit of detection (LOD) and sensitivity for detecting DM RBP4 binding were 0.076 fg/mL and 8.92 nA(g/mL)-1, respectively. This gold nanoparticle decorated SiNWs biosensor performed better than other methods and enabled efficient, accurate, and direct detection of DM. The SiNWs could be used as a distinctive electrical protein biosensor for biological diagnostic purposes. In conclusion, gold nanoparticle deposition offers effective label-free, direct, and high-accuracy DM detection, outperforming previous approaches. Thus, these SiNWs serve as novel electrical protein biosensors for future biological diagnostic applications.

Optimal performance of silicon nanowire solar cells under low sunlight concentration and their integration as bottom cells in III–V multijunction systems

Nanostructured silicon solar cells are designed to minimize costs through reduced material usage while enhancing power conversion efficiency via superior light trapping and shorter charge separation distances compared to traditional planar cells. This study identifies the optimal conditions for nanoimprinted silicon nanowire (SiNW) solar cells to achieve maximum efficiency under low sunlight concentration and evaluates their performance as bottom cells in III–V multijunction solar cell systems. The findings indicate that the SiNW solar cell reaches its peak performance at a concentration factor of 7.5 suns and a temperature of 40°C or lower. Specifically, the absolute conversion efficiency under these conditions is 1.05% higher than that under unconcentrated light. Compared to a planar silicon solar cell under identical conditions, the SiNW solar cell exhibits a 3.75% increase in conversion efficiency. Additionally, the SiNW single-junction solar cell, when integrated in series with a commercial lattice-matched InGaP/GaAs dual-junction solar cell, was tested under unconcentrated sunlight, specifically at one-sun, global air mass 1.5 condition, to assess its viability in one-sun multi-junction solar cell applications. The results suggest that a III–V upper subcell with a smaller active area than that of the SiNW subcell is optimal for maximizing current production, which is favorable to the cost reduction of the device. This hybrid configuration is particularly advantageous for terrestrial applications, such as electric vehicles, which demand lightweight, high-performance multijunction solar cell devices. Although the weight reduction of the characterized SiNW solar cell with a full silicon substrate compared to its planar solar cell counterpart is 1.8%, recommendations to increase this reduction to as much as 64.5% are discussed to conclude this paper.

Highly Photoresponsive Vertically Stacked Silicon Nanowire Photodetector with Biphasic Current Stimulator IC for Retinal Prostheses

This paper presents an integrated approach for a retinal prosthesis that overcomes the scalability challenges and limitations of conventional systems that use external cameras. Silicon nanowires (SiNWs) are utilized as photonic sensors due to their nanoscale dimensions and high surface-to-volume ratio. To enhance these properties and achieve high photoresponsivity, our research team developed a vertically stacked SiNW structure using a fabrication method entirely based on dry etching. The fabricated SiNW photodetector demonstrated excellent electrical and optical characteristics, including linear I–V characteristics that confirmed ohmic contact formation and high photoresponsivity exceeding 105 A/W across the 400–800 nm wavelength range. The SiNW photodetector, following its integration with a switched capacitor stimulator circuit, exhibited a proportional increase in stimulation current in response to higher light intensity and increased SiNW density. In vitro experiments confirmed the efficacy of the integrated system in inducing neural responses from retinal cells, as indicated by an increased number of neural spikes observed at higher light intensities and SiNW densities. This study contributes to sensor technology by demonstrating an approach to integrating nanostructures and electronic components, which enhances control and functionality.

Gold Nanoparticles Decoration of Zinc Oxide Nanowalls on Flexible Substrates

Metal oxide nanostructures decorated with noble metal nanoparticles are hybrid structures with a special interface that combines the unique properties of those two materials. Noble metal nanoparticles exhibit useful catalytic properties, and they can be functionalized with biomaterials. In this work, we use gold nanoparticles that can be functionalized using thiolated molecules bound to the metal surface. Zinc oxide nano-walls (NWs) are a high surface-to-volume ratio wide-bandgap semiconductor nanostructures that, due to their biocompatibility and non-toxicity characteristics, can be used in biosensing applications that involve contact with tissues and cells. ZnO nano-walls can be deposited from aqueous solutions at low temperatures, both on rigid and flexible substrates, using a simple and low-cost process that can be upscaled to high-volume production. In this work, we study the nucleation and growth of the ZnO nano-walls and we describe the gold nanoparticles decoration at three different schemes of surface functionalization. Among these schemes, we found that the process where ZnO nano-walls were deposited on polyimide substrates followed by activation using a self-assembled monolayer, resulted in a decoration with uniform size and distribution of gold nano-particles. That process was studied as a function of the growth temperature, solution concentration, and time. The morphology of the ZnO nano-walls was studied by Scanning Electron microscope imaging and the crystal structure was studied by X-ray diffraction.

E-beam Lithography Technology for Quantum Device Fabrication and Nanoscale Patterning

Currently nanotechnology becoming more important with the implementation of nano devices including quantum devices. In this paper, we will briefly introduce the JEOL JBX-8100FS e-beam lithography tool which was recently installed in Hallym University and the current status of the exposure conditions set up. As applications using e-beam lithography tool, we will introduce Schottky barrier single hole transistor and silicon nanowire thermoelectric device, respectively. We are under researching plasmonic and quantum devices as basic research.

CMOS-Compatible High-Performance Silicon Nanowire Array Natural Light Electronic Detection System.

In this article, we propose a novel natural light detector based on high-performance silicon nanowire (SiNW) arrays. We achieved a highly controllable and low-cost fabrication of SiNW natural light detectors by using only a conventional micromachined CMOS process. The high activity of SiNWs leads to the poor long-term stability of the SiNW device, and for this reason, we have designed a fully wrapped structure for SiNWs. SiNWs are wrapped in transparent silicon nitride and silicon oxide films, which greatly improves the long-term stability of the detector; at the same time, this structure protects the SiNWs from breakage. In addition, the SiNW arrays are regularly distributed on the top of the detector, which can quickly respond to natural light. The response time of the detector is about 0.015 s. Under the illumination of 1 W·m-2 light intensity, multiple SiNWs were detected together. The signal strength of the detector reached 1.82 μA, the signal-to-noise ratio was 47.6 dB, and the power consumption was only 0.91 μW. The high-intensity and highly reliable initial signal reduces the cost and complexity of the backend signal processing circuit. A low-cost and high-performance STM32 microcontroller can realize the signal processing task. Therefore, we built a high-performance SiNW natural optoelectronic detection system based on an STM32 microcontroller, which achieved the real-time detection of natural light intensity, with an accuracy of ±0.1 W·m-2. These excellent test performances indicate that the SiNW array natural light detector in this article meey the requirements of practicality and has broad potential for application.

Deep characterization of the electrical features of Ag/P3HT/SiNWs Schottky diodes by machine learning models based on experimental study

In the present paper, silicon nanowires (SiNWs) surface covered by organic semiconducting polymer (P3HT) were used as the base material for the formation of the Ag/P3HT/SiNWs Schottky diode. Based on Current-Voltage (I-V) experimental study, different machine learning models are used to predict the current output of the Ag/P3HT/SiNWs diode taking into account changes in the applied voltage and immersion time of SiNWs in P3HT polymer solution. We used mathematical, decision tree, and Artificial Neural Network (ANN) models. The ANN model is the best model describing the changes of I-V characteristics with different immersion durations. The ANN, which is a perception layer with 48 neurons in its hidden layer, was trained using real current readings collected at different immersion times in P3HT solution ranging from 30 min to 210 min and voltages from -10 V to +10 V. ANN model achieves a mean squared error of 4.24 10−7, a mean absolute error of 3.82 10−4, a root mean square error of 6.7 10−4, and an R-squared value of 0.999997, indicating its exceptional predictive accuracy. The input layer of the model includes 244 data points representing time and voltage values, while the output layer provides the corresponding values of 844 data points. Using only two hidden layers, this model accurately predicts the current output for the Ag/P3HT/SiNWs Schottky diode. Comparing it with other models, the ANN method offers very accurate and fast predictions.

Ultrasensitive Detection and Wide Dynamic Range Pyrene Quantification Based on Luminescence Restoration of β-Cyclodextrin-Functionalized Silicon Nanowires

Ultrasensitive Detection and Wide Dynamic Range Pyrene Quantification Based on Luminescence Restoration of β-Cyclodextrin-Functionalized Silicon Nanowires

MnOx Embedded in Silicon Nanowire Arrays for High-Performance Supercapacitors

MnOx Embedded in Silicon Nanowire Arrays for High-Performance Supercapacitors

Transverse magneto-optical Kerr effect enhancement in si–ni nanogratings by mie and surface lattice resonances

We demonstrate experimentally that a one-dimensional array of silicon nanowires periodically placed on a nickel substrate enhances the transverse magneto-optical Kerr effect (TMOKE) compared to a nickel film. The enhancement mechanism is associated with the excitation of two types of resonances: multipole Mie resonances in each nanowire and surface lattice resonances (SLRs) emerging from the periodic arrangement of the nanowires. The maximal TMOKE values reached up to 1.9 % and 2.6 % due to the excitation of SLR and a magnetic dipole resonance, respectively. When the SLR is excited, the spectral width of the TMOKE enhancement is narrower compared to the case of the magnetic dipole resonance.

Silicon Nanowires via Metal-Assisted Chemical Etching for Energy Storage Applications.

Silicon nanowires (SiNWs) have demonstrated great potential for energy storage due to their exceptional electrical conductivity, large surface area, and wide compositional range. Metal-assisted chemical etching (MACE) is a widely used top-down technique for fabricating silicon micro/nanostructures. SiNWs fabricated by MACE exhibit significant surface areas and diverse surface chemistry. Since the material composition and surface chemistry have a significant impact on the electrochemical energy storage performance, integrating SiNWs with diverse materials like porous carbon, metal oxides/sulfides, and polymers, can establish composites with excellent properties. Hence, it is imperative to meticulously fabricate SiNW-based materials with customizable morphologies and enhanced electrochemical energy-storage performance. This review provides an in-depth study of recent advancements in SiNW-based materials with enhanced performance for energy storage systems, such as supercapacitors (SCs) and lithium-ion batteries (LIBs). It includes a concise overview of the history, MACE synthesis, and characteristics of SiNWs. Further, it also explores the key elements that influence the MACE process of SiNWs and delves into structural engineering. Additionally, we introduce recent advances in SiNW-based materials for the design of high-performance energy-storage devices, namely SCs and LIBs. Finally, we present the crucial future prospects of SiNW-based materials for energy-storage applications.

Preparation of Si/TiSi2 as high-performance anode material for lithium-ion batteries by molten salt electrolysis

The photovoltaic industry has generated a large amount of silicon cutting waste (SiCW), whose disposal presents an urgent environmental issue. In this study, micron-sized flaky silicon cutting waste was transformed into silicon nanowires, and Si/TiSi2 nanocomposites were synthesized through molten salt electrolysis using photovoltaic SiCW and TiO2 as precursors. Lithium-ion batteries using the resulting composites as an anode exhibited an initial discharge specific capacity of 1936.1 mAh g⁻¹ and an initial Coulombic efficiency (ICE) of 83.99 %. After 200 cycles, its reversible specific capacity reached 1133.8 mAh g⁻¹, surpassing that of the molten salt electrolytic pre-oxidized SiCW (535.5 mAh g⁻¹) and untreated SiCW (385.0 mAh g⁻¹). This study presents a novel approach for modifying silicon-based anode materials while offering a sustainable and environmentally friendly method for recycling photovoltaic silicon waste.

A high-safety lithium-ion battery electrospun separator with Si3N4-assisted sulfonated poly(ether ether ketone) for regulating lithium flux

The uncontrolled lithium (Li) dendrite growth significantly impacts the safety performance of polymer separators. To mitigate this growth, this study introduces Si3N4 into sulfonated poly(ether Ether Ketone) (SPEEK) and prepares Si3N4/SPEEK composite separators via electrospinning. At the interface between the Si3N4/SPEEK separator and the Li anode, the Si nanowires that form impede Li dendrite growth, thereby enhancing the electrochemical performance of lithium-ion batteries (LIBs). The Li deposition test of the 10 % Si3N4/SPEEK separator can operate for 1000 h without short-circuiting. Additionally, the LiFePO4||Li cell with the 10 % Si3N4/SPEEK separator shows improved initial discharge capacity (157.8 mAh g−1 at 1C) and superior rate performance (125 mAh g−1 at 10C). Moreover, the nano-scale Si3N4 endows the separator with robust thermal and mechanical properties. The FLIR observations reveal that the 10 % Si3N4/SPEEK separator maintains uniform thermal distribution and structural integrity even at 300 °C, ensuring safe battery operation at high temperatures. The additional load of the 10 % Si3N4/SPEEK separator can reach 10.2 mN, which enhances the puncture resistance of the separator. This work provides a solid approach for the application of SPEEK as a high-safety and high-rate LIB separator.

Mapping Full Conformational Transition Dynamics of Intrinsically Disordered Proteins Using a Single-Molecule Nanocircuit.

Intrinsically disordered proteins (IDPs) are emerging therapeutic targets for human diseases. However, probing their transient conformations remains challenging because of conformational heterogeneity. To address this problem, we developed a biosensor using a point-functionalized silicon nanowire (SiNW) that allows for real-time sampling of single-molecule dynamics. A single IDP, N-terminal transactivation domain of tumor suppressor protein p53 (p53TAD1), was covalently conjugated to the SiNW through chemical engineering, and its conformational transition dynamics was characterized as current fluctuations. Furthermore, when a globular protein ligand in solution bound to the targeted p53TAD1, protein-protein interactions could be unambiguously distinguished from large-amplitude current signals. These proof-of-concept experiments enable semiquantitative, realistic characterization of the structural properties of IDPs and constitute the basis for developing a valuable tool for protein profiling and drug discovery in the future.

High-density integration of uniform sub-22 nm silicon nanowires for transparent thin film transistors on glass

Ultrathin catalytical silicon nanowires (SiNWs), grown as orderly arrays upon glass substrates, are ideal 1D channels for the construction of high-performance field effect transistors for low-power and high aperture/transparency electronics. In this work, a rather uniform growth integration of high-density ultrathin SiNWs has been accomplished directly on glass substrate at 290 °C, via an in-plane solid–liquid-solid mechanism. The indium (In) catalyst thickness deposited on the dense guiding terrace steps was identified as a key parameter to suppress the size dispersion of the In droplets, and thus enable a uniform growth of ultrathin SiNWs with diameters down to DNW=21.8 ± 1.8 nm, a close-to-unity guided growth rate and an excellent transparency > 90 % in spectrum ranging from 350 nm to 950 nm. Based on a convenient dry plasma etching and low-temperature passivation procedure, high-performance SiNW transistors have been successfully fabricated upon a dense array of parallel SiNWs as channels with a narrow NW-to-NW spacing of 100 nm. A high current ratio Ion/Ioff > 107, a low off-state current down to 0.1 pA, a steep subthreshold swing of SS∼120 mV dec-1 and excellent positive and negative bias stabilities have been demonstrated, as well as SiNW-based inverter logics that achieve a gain of 14.6 V/V under a drive voltage of 2.25 V. These results highlight the potential of catalytic SiNWs to serve as advantageous 1D channels for large-area display or transparent electronics.