Silicon Nanowire: Advancing Nanoscale Devices and Systems

Chapter 1: Silicon nanowire

Nanowires made of silicon, also known as SiNWs, are a type of semiconductor nanowire that are often generated from a silicon precursor through etching of a solid or through catalyzed growth from a vapor or liquid phase. Silicon nanowires are also referred to as SiNWs. In the fields of thermoelectrics, sensors, and lithium-ion batteries, nanowires like these have the potential to be extremely useful. The initial synthesis of SiNWs is frequently accompanied by multiple phases of thermal oxidation in order to produce structures that have a size and morphology that can be precisely adjusted.

Silicon nanowires (SiNWs) possess distinctive characteristics that are not observed in bulk (three-dimensional) silicon objects. These features are the result of an unusual electronic structure that is quasi-one-dimensional, and they are the topic of research in a wide variety of fields and applications. SiNWs are regarded as one of the most significant one-dimensional materials due to the fact that they have the potential to serve as building blocks for nanoscale electronics that are created without the requirement for fabrication facilities that are both sophisticated and expensive. SiNWs are often investigated for their potential uses, which include photovoltaics, nanowire batteries, thermoelectrics, and non-volatile memory, among others.

Silicon nanowires are a prospective candidate for a wide range of applications that draw on their distinctive physico-chemical features, which differ from those of bulk silicon material. This is because silicon nanowires possess unique physical and chemical properties.

Because of their charge trapping activity, SiNWs are useful in applications that require electron hole separation, such as photovoltaics and photocatalysts. This is because SiNWs display charge trapping behavior. During the past several years, the power conversion efficiency of SiNW solar cells has experienced a remarkable improvement, going from less than 1% to more than 17%. This development is a result of recent experiments conducted on nanowire solar cells.

The ability for lithium ions to intercalate into silicon structures renders certain Si nanostructures of interest towards uses as anodes in Li-ion batteries (LiBs). SiNWs are particularly advantageous for use as such anodes since they are able to sustain considerable lithiation while still preserving their structural integrity and electrical connection.

This is because silicon nanowires combine a high electrical conductivity, which is related to the bulk properties of doped silicon, with a low thermal conductivity, which is due to the narrow cross section. This combination makes silicon nanowires an excellent thermoelectric generator.

Charge trapping behavior and tunable surface governed transport properties of SiNWs render this category of nanostructures of interest towards use as metal insulator semiconductors and field effect transistors, where the silicon nanowire is the main channel of the FET which connect the source to the drain terminal, facilitating electron transfer between the two terminals with further applications as nano-electronic storage devices, in flash memory, logic devices as well as chemical, gas and biological sensors.

Because of their excellent physical qualities, including as high carrier mobility, high current switch ratio, and close to optimal subthreshold slope, SiNWFET has created widespread worry in the sensor industry ever since it was originally described in 2001. This is due to the fact that SiNWFETs have those characteristics. Due to the fact that it is integrated with CMOS fabrication technology, it is not only cost-effective but also has the potential to be created on a big scale manufacturing. In particular, SiNWFET has a high sensitivity and specificity to biological targets, and it has the potential to enable label-free detection after being changed with small biological molecules to match the target item. This is particularly useful in the field of biorelated research. Furthermore, SiNWFET could be produced in arrays and selectively functionalized, which would allow for the simultaneous detection and analysis of many targets. This would be a significant advancement. The throughput and efficiency of biodetection could be significantly improved with the use of multiplexed detection.

For SiNWs, there are a few different synthesis methods that are known to exist. These methods can be broadly classified into two categories: top-down synthesis, which involves starting with bulk silicon and removing material in order to produce nanowires, and bottom-up synthesis, which involves using a chemical or vapor precursor in order to construct nanowires.

The production of nanostructures from a bulk precursor is accomplished by the utilization of material removal techniques.

Ion-beam etching, laser beam ablation, and thermal evaporation oxide-assisted growth (OAG) are the two techniques that are utilized.

- Metal-assisted chemical etching, often known as MaCE

- Vapour–liquid–solid (VLS) growth is a kind of catalyzed chemical vapor deposition (CVD) that frequently makes use of silane as SI precursor and gold nanoparticles as catalyst (or'seed').

Molecular beam epitaxy is a type of photovoltaic, or PVD, that is performed in a plasma environment.

- Precipitation from a solution is a version of the VLS method that is appropriately dubbed supercritical fluid liquid solid (SFLS). This approach makes use of a supercritical fluid (for example, organosilane at high temperature and pressure) as the precursor for silicon rather than vapor. A colloid in solution, such as colloidal gold nanoparticles, would serve as the catalyst, and the SiNWs would be generated in this solution.

Thermal oxidation processes are frequently conducted after initial silicon nanostructures have been obtained through physical or chemical processing, either top-down or bottom-up. This is done in order to generate materials with the required size and aspect ratio. Nanowires made of silicon have a self-limiting oxidation behavior that is both unique and beneficial. This behavior is characterized by the fact that oxidation essentially stops due to diffusion constraints, which can be modeled. Through the utilization of this phenomena, it is possible to achieve high aspect ratio SiNWs with diameters that are less than 5 nm. This phenomenon also enables accurate control of dimensions and aspect ratios in SiNWs. Utilizing the self-limiting oxidation of SiNWs is beneficial for the development of materials for lithium-ion batteries.

Because of their one-of-a-kind features and the fact that they can be controlled in terms of size and aspect ratio with a high degree of precision, SiNWs are attracting a lot of attention. Limitations in large-scale fabrication continue to be a barrier to the widespread adoption of this material throughout the entire spectrum of applications that have been researched. Combined studies of synthesis methods, oxidation kinetics and properties of SiNW systems aim to overcome the present limitations and facilitate the implementation of SiNW systems, for example, high quality vapor-liquid-solid–grown SiNWs with smooth surfaces can be reversibly stretched with 10% or more elastic strain, approaching the theoretical elastic limit of silicon, which could open the doors for the emerging elastic strain engineering and flexible bio-/nano-electronics.

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Chapter 2: Silicon nanotube

Silicon nanotubes are nanoparticles that are formed from silicon atoms and have the structure of a tube. In the same way as silicon nanowires are technologically significant, these materials are also significant because of their peculiar physical properties, which are fundamentally different from those of bulk silicon. In the vicinity of the year 2000, the initial reports on silicon nanotubes were published.

Utilizing a reactor that makes use of an electric arc and does not require the utilization of any catalyst is one way for the manufacture of silicon nanotubes. After the reactor has been evacuated and filled with the nonreactive noble gas argon, the purity of the product is ensured. Chemical vapor deposition is the method that is responsible for the actual creation of the nanotubes by themselves.

The use of nanowires made of germanium, carbon, or zinc oxide as a template is a method that is more commonly used in laboratory settings. After that, silicon, which is commonly derived from silane or silicon tetrachloride gas, is coated onto the nanowires. Thereafter, the core is dissolved, leaving behind a silicon tube. The second approach allows for precise control over the growth of template nanowires, silicon deposition and nanowire etching, and consequently the shape of the Si nanotubes that are produced as a result. However, the smallest inner diameter that can be achieved is restricted by tens of nanometers.

When it comes to growing one-dimensional silicon nanostructures, the most popular methods are the standard vapor-liquid-solid (VLS) and solid-liquid-solid (SLS) mechanisms. On the other hand, they typically only include a single kind of metal as a catalyst, and as a result, they are not suitable for the cultivation of tubular (hollow) silicon nanostructures. Recently, an attempt has been made to take advantage of the uneven development rate of constituent metal catalysts by employing a bilayer catalyst layer consisting of nickel and gold. The growth of multiwall silicon nanotubes with a sidewall thickness of a few nanometers has been accomplished through the utilization of these modified VLS and SLS techniques.

Silicon nanotubes and nanowires have been studied for use in electronics, such as thermoelectric generators, because to their ballistic conductivity. This has led to the possibility of their widespread application. It would appear that silicon nanoparticles may behave like a metal fuel due to the fact that the structure is able to contain molecules of hydrogen, which would make it similar to coal but without the CO2 that is present. In the process of delivering energy, a silicon nanotube that has been charged with hydrogen leaves behind water, ethanol, silicon, and sand as unwanted byproducts. The generation of hydrogen, on the other hand, takes a significant amount of energy; hence, this is merely a way of storing energy and not a method of manufacturing hydrogen.

There is the potential for lithium-ion batteries to make use of silicon nanotubes and silicon nanowires. Graphitic carbon is used as the anode in conventional Li-ion batteries; however, replacing graphitic carbon with silicon nanotubes has been shown to enhance the specific (by mass) anode capacity by a factor of ten. However, the overall capacity improvement is lower due to the significantly lower specific cathode capacities.

Light emission is yet another emerging application of photonic nanotubes made of silicon. Due to the fact that silicon is a semiconductor with an indirect band gap, the quantum yield of radiative recombination in this material is extremely low. Due to the quantum confinement effect, the quantum efficiency of light emission from silicon-based nanostructures increases when the thickness of these structures decreases below the effective Bohr radius, which is approximately 9 nanometers in silicon. Through the utilization of this particular characteristic, it has been proved that silicon nanotubes with extremely thin sidewalls possess the ability to emit light.

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Chapter 3: Zinc oxide

The chemical formula for zinc oxide is ZnO. Zinc oxide is an inorganic substance. It is a powder that is white in color and does not dissolve in water. In a wide variety of materials and products, zinc oxide is utilized as an additive. Some examples of these include cosmetics, food supplements, rubbers, plastics, ceramics, glass, cement, lubricants, paints, sunscreens, ointments, adhesives, sealants, pigments, foods, batteries, ferrites, fire retardants, semi conductors, and first-aid tapes. Zinc oxide is manufactured synthetically the majority of the time, despite the fact that it is found in nature as the mineral zincite.

It is 1314-13-2 Y.

The image is interactive.

It is CHEBI:36560 Y.

This is ChEMBL3988900Y.

- 14122 Yarn

It is DB09321

The number is 215-222-5.

- C12570 --

The number 14806

- The ZH4810000

It is SOI2LOH54Z Y.

Number: DTXSID7035016

The key is XLOMVQKBTHCTTD-UHFFFAOYSA-N Y. The inChI value is 1S/O.Zn.

[Zn] is equal to O

TWA 5 mg/m3 and ST 10 mg/m3 are the fume levels.

There is a possibility that early people utilized zinc compounds in both processed and unprocessed forms, such as paint or therapeutic ointment; however, the composition of these compounds is unknown. In the Indian medical classic known as the Charaka Samhita, which is believed to have been written around 500 BC or earlier, it is indicated that pushpanjan, which is most likely zinc oxide, can be used as a salve for treating open wounds and eyes. On the other hand, the Greek physician Dioscorides, who lived in the first century AD, makes reference to zinc oxide ointment. As Avicenna did in his book The Canon of Medicine, Galen proposed using zinc oxide as a treatment for tumors that progress to ulceration. items such as infant powder and creams against diaper rashes, calamine lotion, anti-dandruff shampoos, and antiseptic ointments all contain it as a component. Other items that contain it include antiseptic