Hydrogen-terminated Si

Scheme 20 Hydrosilylation of an alkene by hydrogen-terminated Si(l 11) surface.

Why do we believe that a Cu monolayer is inserted between SAM and gold substrate The 2D-deposit grows and dissolves extremely slowly. Another indication is that the 2D deposit is very stable and shows no displacement by the scanning tip. Cu clusters on top of an alkanethiol-SAM would be only weakly bound and should be easily pushed away by the tip at higher tunnel currents, very much like metal clusters on a hydrogen-terminated Si(lll) surface, which for that very reason are difficult to image by STM (or AFM [122]). And finally, the cyclic voltammograms (Fig. 33) point to the formation of a buried monolayer . 

Figure 8.3 Hydrogen-terminated Si(l 11), Si(lOO) and porous silicon surfaces.

Therefore, surface modification strategies for the formation of direct silicon-carbon bonds require, first, a special pre-treatment of the silicon surface to prevent oxidation and, second, an activation of the silicon surface for subsequent reaction with organic moieties. This has been achieved by treatment of the silicon surface with hydrofluoric acid to generate a hydrogen-terminated Si(lll) surface, which can further react with unsaturated co-functionahzed alkenes in the presence of UV irradiation or by thermal activation [27,44,45]. Using this method, carboxylic acid modified silicon substrates have been successfully generated and coupled to thiol modified ONDs via a polylysine/sulfosuccinimidyl 4-(M-maleimidomethyl)-cyclohexane-l-carboxylate couphng (Fig. 12). 

Figure 5.6. STM image of a hydrogen-terminated Si(lll) surface. The image shows a 10 nm x 10 nm region of the surface, from Ref. [20]. Reproduced by permission of the Royal Society of Chemistry.

Quayum, M. E., Kondo, T., Nihonyanagi, S., Miyamoto, D. and Uosaki, K. Formation of organic monolayer on a hydrogen terminated Si(l 11) surface via silicon-carbon bond monitored by ATR FT-IR and SFG spectroscopy Effect of orientational order on the reaction rate. Chemistry Letters, 208 (2002). 

Table 1. Interactions of various adsorbates with a hydrogen terminated Si(100)-2 x 1 surface. References are primarily related to atomic scale STM investigations.

Y. Terada, B.-K. Choi, S. Heike and M. Fujimori, Injection of molecules onto hydrogen terminated Si(100) surfaces via a pulse valve, J. Appl. Phys. 93, 10014 (2003). 

S. Watanabe, N. Nakayama, and T. Ito, Homogeneous hydrogen-terminated Si(lll) surface formed using aqueous HE solution and water, Appl. Pkys. Lett. 59(12), 1458, 1991. 

Ohira, T., Ukai, O., Adachi, T, Takeuchi, Y, and Murata, M., Molecular-dynamics simulations of SiHs radical deposition on hydrogen-terminated Si(lOO) surfaces. Phys. Rev. B 52, 8283-8287 (1995). 

The attachment of ODNs to silicon wafers is described in which hydrogen terminated Si(III) surfaces are modified with (o-unsaturated alkyl esters. Deprotection with tBuOK yielded a carboxyl modified surface, which was used to attach DNA. The silicon wafers were shown to exhibit excellent specificity and stability. UV-mediated attachment of alkenes has been used to functionalise silicon surfaces using t-BOC protected 10-aminodec-l-ene. After removal of the... 

The dispersion and assembly behavior of silicon (Si) nanoclusters are controlled in organic and aqueous suspensions. Hydrogen-terminated Si nanoclusters are stably dispersed in non-polar solvents, but assemble on aqueous suspension surfaces. The nanoclusters spontaneously pack into lattice arrangements when a slow assembly rate is maintained. In addition, converting the nanocrystal surface to carboxylic acid termination stably disperses the nanocrystals in aqueous suspensions. They show size-dependent photoluminescence (PL) from yellow to green in the suspensions, while partly oxidizing the surface causes blue PL. 

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