Silicon surface functionalization

A step-by-step surface assembly utilizes poly-N-succinimidyl acrylate attached to a gold coated AFM (atomic force microscope) tip in conjunction with a silicon surface functionalized with a primary amino group. Retracting the AFM tip breaks the Au-C bond, leaving the polymer attached to the silicon surface. ... 

Dattilo D, Armelao L, Maggini M, Fois G, Mistura G (2006) Wetting behavior of porous silicon surfaces functionalized with a fulleropyrrolidine. Langmuir 22 8764-8769... 

In Section V, a general discussion of how silicon surfaces can be used to obtain monolayers is presented. The functionalization of silicon surfaces using radical chemistry is an area of intense and active investigation because of the potential for a myriad of practical applications.In order to help those readers who are not familiar with silyl radical chemistry, we discuss some general aspects of silyl radicals in Section II, together with some recent findings. 

The radical-based functionalization of silicon surfaces is a growing area because of the potential practical applications. Although further knowledge is needed, the scope, limitations, and mechanism of these reachons are sufficiently well understood that they can be used predictably and reliably in the modification of hydrogen-terminated silicon surfaces. The radical chemistry of (TMSlsSiH has frequently served as a model in reactions of both hydrogen-terminated porous and flat silicon surfaces. We trust that the survey presented here will serve as a platform to expand silicon radical chemistry with new and exciting discoveries. 

Wet preparation of metal nanoparticles and their covalent immobilization onto silicon surface has been surveyed in this manuscript. Thiol-metal interaction can be widely used in order to functionalize the surface of metal nanoparticles by SAM formation. Various thiol molecules have been used for this purpose. The obtained functionalized particles can be purified to avoid the effect of unbounded molecules. On the other hand, hydrogen-terminated silicon surface is a good substrate to be covered by Si-C covalently bonded monolayer and can be functionalized readily by this link formation. Nanomaterials, such as biomolecules or nanoparticles, can be immobilized onto silicon surface by applying this monolayer formation system. 

Fig. 59. Molecular modification of semiconductor silicon surfaces. Removal of the oxide generates a hydrogen-terminated layer that reacts with a range of molecular functional groups including alkenes. 

In an effort to understand silicon surface diffusion, NoorBatcha, Raff and Thompson have employed molecular dynamics to model the motion of single silicon atoms on the Si(001) and Si(lll)surfaces. Morse functions are used for the pair forces, with the parameters being determined by the heat of sublimation. Because different forces were used for the diffusing and substrate atoms, the incorporation of gas-phase species into the crystal could not be directly modeled. Nonetheless, they were able to explore the characteristics of adsorption and diffusion for single atoms. 

Fig. 8.n Covalent coupling of trypsin to a silicon surface. In a first step, free silanol groups are reacted with 3-amino-propyltriethoxysilane. The amino-functionalized surface is then treated with 2,4,6-trichloro-1,3,5-triazine (cyanuric chlorid). Finally, trypsin is covalently bound via a free amino group of the protein. 

Other Lewis acid-catalyzed hydrosilylations of alkenes and alkynes on hydride-terminated silicon surfaces result in a surface modified with alkyl and alkenyl functionalities. ... 

The Silicon Surface and its Activation with (u-functionalized Alkenes. .. 90... 

Silicon wafers can act as substrates in the fabrication of DNA arrays. Chemical functionalization of silicon surfaces is compUcated by the fact that silicon spontaneously oxidizes in air to produce an amorphous sihca layer. 

Figure 6.9 A schematic representation of orthogonal process for nanoparticles self-assembly (a) a patterned silicon wafer with Thy-PS and PVMP polymers fabricated through photolithography and (b) orthogonal surface functionalization through Thy-PS/DP-PS recognition and PVMP/acid-nanoparticle electrostatic interaction. Reprinted with permission from Xu et al. (2006). Copyright 2006 American Chemical Society.

The first surface-initiated enzymatic polymerization reported was the synthesis of amylose brushes on planar and spherical surfaces [145]. For this, silica or silicone surfaces were modified with self-assembled monolayers of (3 amino-propyl)trimethoxysilane or chlorodimethylsilane, respectively. To these functionalities, oligosaccharides were added via (a) reductive amidation of the oligosaccharides to surface-bound amines, (b) conversion of the oiigosaccharide to the according aldonic acid lactone and reaction with surface bound amines, and (c) incorporation... 

It was demonstrated that reproducible gas-sensitive silicon Schottky sensors could be produced after terminating the silicon surface with an oxide layer [71, 72]. This interfacial oxide layer permits the device to function as a sensor, but also as a diode, as the charge carriers can tunnel through the insulating layer. The layer made the Schottky diode behave like a tunneling diode, and the ideality factor could be voltage-dependent [73]. 

Fig. 3.5. Silicon etch rate as measured with a quartz crystal microbalance as a function of the bias voltage applied to the silicon surface in CF4 and Ar glow discharges. The discharge intensity was not significantly influenced by the application of the negative voltage to the silicon surface...

Linford and coworkers have shown that the attachment of alkenes to H-terminated silicon surfaces can also be initiated by direct mechanical scribing, in a process termed chemomechanical functionalization [145-147]. The reaction of 1-alkenes (as well as 1-alkynes) leads to attachment of the molecule to the surface through two new Si—C bonds. The proposed mechanism is the mechanical cleavage of Si—H and Si—Si bonds, leading to silicon radicals that then react with the reactive liquid. Interestingly, Linford and coworkers have also extended this work to show that chemomechanical functionalization can be carried out not only on H-terminated Si, but also on sihcon covered with oxide, and have shown that the process works with a variety of halides, alcohols, and epoxides in both the liquid and gas phase [146]. 

In a noteworthy application, Hamers and coworkers recently extended the radical-based chemistry developed for the silicon surfaces to functionalize gallium nitride surfaces for eventual use in biosensing [152]. In those experiments, a GaN(OOOl) surface was first terminated by hydrogen using a hydrogen plasma, then exposed to... 

Buriak, J. M. Organometallic chemistry on silicon surfaces formation of functional monolayers bound through Si-C bonds. Chemical Communications, 1051 (1999). 

Wacaser, B. A., Maughan, M. J., Mowat, I. A., Niederhauser, T. L., Linford, M. R. and Davis, R. C. Chemomechanical surface patterning and functionalization of silicon surfaces using an atomic force microscope. Applied Physics Letters 82, 808 (2003). 

Song, J. H. and Sailor, M. J. Functionalization of nanocrystalline porous silicon surfaces with aryllithium reagents Formation of silicon-carbon bonds by cleavage of silicon-silicon bonds. Journal of the American Chemical Society 120, 2376 (1998). 

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