SiNWs, or silicon nanowires, are usually made from a silicon base material using catalyzed growth or by etched solid form from either a liquid or gaseous state.

In terms of area, nanowires are nanostructures with diameters in the nanometer range. Nanowires that are insulating (TiO2, SiO2), semiconducting (GaN, InP, Si), and conducting (Au, Pt, Ni) have a wide range of real-world applications. The two primary methods for making nanowires are top-down and bottom-up processes. The bottom-up method is best for producing nanowires because it allows precise control over important parameters like growth direction, chemical composition, doping level, length, and radius. The bottom-up method is determined by chemical composition. However, the nanowires are still in the experimental stage and have not yet been put to use in any real-world situations.

Properties of SiNWs

  • Thermal Properties 

Silicon nanowires are not straight and have a curved shape when used in experiments or applications. The changes in their thermal conductivity and phonon transport can both be affected by their curvature. Because the phonons deviate from the primary heat flow direction when they pass through the nanowire axially, the curvature of the nanowire acts as impedance to the transport of phonons. The thermal conductivity decreases when the nanowire curvature radius becomes smaller.

The curvature has a greater impact on the thermal impedance when its radius is one order smaller than the phonon means a free path. The fact that the silicon nanowire's thermal conductivity can be controlled through the proper shaping of the wire is an intriguing observation.

  • Chemical Properties

Natural oxidation is a significant chemical reaction that makes silicon nanowires extremely beneficial for transistor and sensor applications. Because oxygen causes effects on the surface of the pure semiconductor nanowire core, this effect cannot be avoided. When the SiO layer is chemically modified, the hole motility of the silicon nanowire can be increased up to twice as much.

  • Optical Properties

The nanowires can exhibit mechanical strain effects when exposed to light due to their photo elastic properties, as light has a wavelength that is proportional to its energy band gap.

  • Mechanical Properties

The electrical conductivity of the nanowire can be changed by internal dislocations that are caused by external stress, strain, and temperature changes. Therefore, the nanowire's mechanical characteristics are crucial to devising a processing method. Electro-migration and delamination can cause issues with the amount of tensile and compressive stresses generated during VLSI (Very Large Scale Integration) processing. Nanowires have interesting mechanical properties due to their low defect count per unit length and high aspect ratio in comparison to bulk materials, according to the findings.

Systems of one dimension are nanowires. Nanowires are utilized in sensors and NEMS (nano-electromechanical systems) applications. Due to their high Young Modulus and tensile strength, these materials are extremely durable and capable of storing elastic energy. Additionally, silicon nanowires with high oscillating frequencies can construct nanoscale resonators due to their remarkable elastic properties.

Applications of SiNWs

Because of their versatile chemical and physical properties, silicon nanowires have a broad range of applications that would benefit from their impressive physicochemical abilities. They differ from the silicon normally used in computer chips in several key ways. The silicon nanowires exhibit charge-trapping behavior, which results in such value systems for electron-hole separation-required applications as photocatalysts and photovoltaics. These qualities make silicon nanowires appealing to be used in organic sensors, compound sensors, rationale gadgets, and blaze memory, as field-impact semiconductors, metal-cover semiconductors, and nanoelectronic stockpiling gadgets.

  • Single Virus

Detecting a single virus molecule presents a challenge for SiNW biosensors and is an important medical fact. In an experiment, the surface of the p-type SiNW sensor was observed to be covered by an antibody receptor.

  • pH

PH detecting is detecting the convergence of hydrogen particles. A p-type SiNW can detect hydrogen ions when its surface is modified with 3-aminopropyltriethoxysilane. The SiNW's surface charge is altered as a result of the catalyst role played by the amino and silanol groups.

  • Glucose 

The detection of glucose has also been reported. The surface oxide layer of a silicon nanowire is changed with the assistance of the enzyme glucose oxidase (GOx). At the point when glucose was close to the nanowire's surface, there were perceptions of an adjustment in the conductance of the silicon nanowire.

  • Proteins

Biotin is a molecule that is used as a binding material for proteins to detect streptavidin, a protein. Because it is very selective for this protein, biotin is used. When the protein reaches the silicon nanowire's surface, its conduction increases rapidly until it reaches a constant value. The SiNW sensor's high sensitivity and selectivity are demonstrated by the fact that the conductance does not change in the absence of the biotin molecule.

  • DNA

When the uncharged peptide nucleic acid (PNA) serves as the bonding material on the surface of the p-type SiNW, DNA can be detected. PNA could only bind to wild-type DNA because of its design. The conductance of silicon nanowires quickly rises as a result of DNA's negative charge.

  • Drug Discovery 

It is important to develop pharmaceuticals to discover new drugs. The change in conductance of silicon nanowires is used to evaluate how well the organic molecule can bind to the enzyme or protein. Although this process is similar to ones done before, it differentiates itself with more practical use. As a result, SiNW sensors make it possible to quickly and easily characterize the drugs.

Bottom Line

In conclusion, silicon nanowires can be grown with high precision using bottom-up methods. Silicon nanowires can be used in the development of the next generation of nanostructures because of their superior properties to those of other nanomaterial. Nanowires are strong and elastic, making them ideal for a variety of applications. Thanks to these attributes, spotting it has become as easy as finding a needle in a haystack. This is a significant advancement that has the potential to have a significant impact on the diagnosis of diseases and the discovery of new drugs. Additionally, the SiNW electrochemical sensors provide a direct electrical readout that does not require the use of costly or time-consuming chemical labeling detection.