Hydrogen-terminated silicon surface is a chemically passivated

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

where the surface Si atoms are bonded to hydrogen. The hydrogen-terminated surfaces are hydrophobic, luminescent, and amenable to chemical modification. Hydrogen-terminated silicon is an intermediate in the growth of bulk silicon from

silane Silane is an inorganic compound with chemical formula, . It is a colourless, pyrophoric, toxic gas with a sharp, repulsive smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Sila ...

: :SiH₄ → Si + 2H₂

Preparation

Silicon wafers are treated with solutions of electronic-grade

hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepr ...

in water, buffered water, or alcohol. One of the relevant reactions is simply removal of silicon oxides: :SiO₂ + 4 HF → SiF₄ + 2 H₂O The key reaction however is the formation of the hydrosilane functional group.

atomic force microscope Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the opt ...

(AFM) has been used to manipulate hydrogen-terminated silicon surfaces.

Properties

Hydrogen termination removes

dangling bond In chemistry, a dangling bond is an unsatisfied valence on an immobilized atom. An atom with a dangling bond is also referred to as an immobilized free radical or an immobilized radical, a reference to its structural and chemical similarity to a f ...

s. All surface Si atoms are tetrahedral. Hydrogen termination confers stability in ambient environments. So again, the surface is both clean (of oxides) and relatively

inert Inert may refer to: * Chemically inert, not chemically reactive ** Inert gas ** Noble gas, historically called inert gas * Inert knowledge, information which one can express but not use * Inert waste, waste which is neither chemically nor biol ...

. These materials can be handled in air without special care for several minutes. The Si-H bond in fact is stronger than the Si-Si bonds. Two kinds of Si-H centers are proposed, both featuring terminal Si-H bonds. One kind of site has one Si-H bond. The other kind of site features SiH₂ centers. Like organic hydrosilanes, the H-Si groups on the surface react with terminal

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s and diazo groups. The reaction is called

hydrosilylation Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds."Hydrosilylation A Comprehensive Review on Recent Advances" B. Marciniec (ed.), Advances in Silicon Science, Springer Science, 2009 ...

. Many kinds of organic compounds with various functions can be introduced onto the silicon surface by the hydrosilylation of a hydrogen-terminated surface. The infrared spectrum of hydrogen-terminated silicon shows a band near 2090 cm⁻¹, not very different from νSi-H for organic hydrosilanes.

Potential applications

One group proposed to use the material to create digital circuits made of

quantum dot Quantum dots (QDs) are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology. When the q ...

s by removing hydrogen atoms from the silicon surface.

References

External links

* * {{DEFAULTSORT:Hydrogen-Terminated Silicon Surface Materials Nanotechnology Thin films Supramolecular chemistry Self-organization

Preparation

Properties

Potential applications

See also

References

External links