The addition of functional groups to silicon via hydrosilation of 1-alkynes at hydrogen-terminated, 1   1 reconstructed, (100) silicon surfaces

Abstract

This work presents a study based on x-ray photoelectron spectroscopy of the reaction of hydrogen-terminated silicon with 1-alkynes as a route for the functionalization of the (100) surface of silicon. The study (i) demonstrates that the grafting of hydrocarbon moieties is possible by simple exposure of the silicon surface to a liquid alkyne, (ii) shows that the derivatization protects the silicon against oxidation in air, (iii) indicates that the process occurs via hydrosilation of the alkyne at the hydrogen-terminated surface and (iv) suggests that grafted moieties contain in large part an unreacted π bond.

Wet chemical routes to the assembly of organic monolayers on silicon surfaces via the formation of Si–C bonds: surface preparation, passivation and functionalization

“…92 For Si (100), the material that is currently used in the majority of semiconductor devices largely because of a fortunate matching of the interatomic spacing of silicon atoms with the lattice constant of silicon dioxide, 95 the preparation of monoand di-hydrogen terminated and atomically flat surfaces can only be achieved with UHV techniques. This is most commonly achieved by exposing either a reconstructed Si(100)-(2 Â 1) 96 (pairing of dangling bonds on adjacent atoms 97 ) or (un)reconstructed Si( 100)-(1 Â 1), [98][99][100] to molecular hydrogen at high temperatures. If prepared outside of the UHV chamber, as in device-quality surfaces, 99 the hydrofluoric acid-etched hydrogen-terminated Si(100) surface is best described as having a complex 101 mono-, di-and tri-hydride configuration 75,77,102 with minor oxygenated defect sites.…”

“…This is most commonly achieved by exposing either a reconstructed Si(100)-(2 Â 1) 96 (pairing of dangling bonds on adjacent atoms 97 ) or (un)reconstructed Si( 100)-(1 Â 1), [98][99][100] to molecular hydrogen at high temperatures. If prepared outside of the UHV chamber, as in device-quality surfaces, 99 the hydrofluoric acid-etched hydrogen-terminated Si(100) surface is best described as having a complex 101 mono-, di-and tri-hydride configuration 75,77,102 with minor oxygenated defect sites. Because of the anisotropic nature of the ammonium fluoride etching, and in agreement with early spectroscopic data, 103 this etching procedure has been generally limited to the (111) orientation since it is generally believed to lead to roughening of the (100) surface.…”

Hydrosilation of 1-alkyne at nearly flat, terraced, homogeneously hydrogen-terminated silicon (100) surfaces

“…The first peak, centred on ¾283.7 eV, is referred to as C and attributed to carbon in carbide configuration; the second peak, centred on ¾285.0 eV, is referred to as C 0 and attributed to carbon in -CH 3 , -CH 2 -or -CH CH-configurations (an unterminated bond intends bonding to carbon); the last peak, centred on ¾286.5 eV, is referred to as C C and attributed to oxidized carbon, irrespective of the fact that carbon is otherwise bonded to silicon or not. 24 The widths of all such lines are consistent with only one oxidation state: the attribution of C C to carbon bonded with a single bond to one oxygen is trivial (so that we can pose C C D C 1 , where the upper index may be interpreted as a kind of oxidation number) but for C the attribution is not straightforward. The hydrosilation of 1-alkynes at 1 ð 1 H Si(100) is expected to occur according to pathways II, III or IV in Fig.…”

“…A study based on contact angle, x-ray reflectivity and infrared absorption spectroscopy of the derivatization with long 1-alkynes (from C 12 to C 18 ) of (100) surfaces prepared via HF aq etching of thermally grown SiO 2 was conducted by Sieval et al 22 A preliminary study of the derivatization with 1-octyne of (100) surfaces prepared by baking an HF aqetched surface at 1100°C in H 2 was conducted by this collaboration based on x-ray photoelectron spectroscopy (XPS) 23,24 only. This paper is devoted to the latter system, extending the characterization of the hydrogen-terminated surface to atomic force microscopy (AFM) and infrared absorption spectroscopy (IRAS).…”

Terascale integration via a redesign of the crossbar based on a vertical arrangement of poly-Si nanowires

“…Since they are based on the properties of conformal deposition (characteristic of poly-Si chemical vapour deposition and oxidation) and directional etching (sputtering or reactive ion etching), the MSPTs are mainly targeted to the definition of poly-Si nanowires. Moreover, silicon is particularly interesting for molecular electronics because it can be terminated with organic moieties carrying wanted electrical properties (like reprogrammable molecules with two well separated conduction states) bonded to the silicon via environmentally robust Si-C bonds [15]. The MSPTs have succeeded in the preparation of silicon wire arrays with pitch p on the 10-nm length scale [16][17][18][19][20][21][22][23][24]: nanowires with width of 7 nm and arrays with p = 35 nm have actually been reported [17,18], whereas the most dense crossbar hitherto produced had a bit density of the order of 10 10 cm −2 [25].…”