Monolayers of 1-Alkynes on the H-Terminated Si(100) Surface

Abstract

Monolayers of a series of 1-alkynes, from 1-dodecyne to 1-octadecyne, have been prepared on the hydrogen-terminated Si(100) surface via a thermal reaction of the organic compound with this Si surface. An efficient procedure is presented for the synthesis of 1-alkynes from the corresponding 1-alkenes. The resulting monolayers were characterized by water contact angle measurements, ATR infrared spectroscopy, and X-ray reflectivity. The results show that these 1-alkynes give well-ordered, covalently bonded monolayers, which are at least as ordered as those of the corresponding 1-alkenes. The exact binding geometry of the 1-alkyne to the Si surface was investigated. The results from IR spectroscopy and X-ray reflectivity measurements indicate that the 1-alkynes form two Si−C bonds to the surface per reacting molecule. Quantum mechanical calculations confirm that this formation of two Si−C bonds is not only chemically possible but also energetically much more favorable than formation of only one Si−C bond per reacting molecule.

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

“…1600 cm À1 FTIR vibration (Si-CQC stretch) for the 1-alkyne hydrosilylation on Si(111)-H of Linford and Chidsey. 31 It is important to comment on the findings of Sieval et al 125 on the thermal reaction of 1-alkynes onto a non-rigorous dihydride phase (i.e. hydrofluoric acid-etched and not otherwise treated Si(100) surface).…”

Covalently Attached Monolayers on Hydrogen‐Terminated Si(100): Extremely Mild Attachment by Visible Light

“…[17] Table 1 lists the static water contact angle of the surfaces modified by a variety of 1-alkenes, 1-alkynes, and two westerified-1-alkenes (compounds I, and II) by using this mild procedure, together with the corresponding results of the thermal radical reaction. [17] These results indicate that visiblelight attachment yields monolayers with properties similar to those obtained from thermal radical reactions, [18] without the disadvantage of requiring a high temperature (165 8C). This has also been confirmed by using attenuated total reflection infra red (ATRIR) spectroscopy, which provided clear peaks for, for example, the antisymmetric and symmetric CH 2 stretching vibrations.…”

Organic Surface Modification of Silicon Nanowire-Based Sensor Devices

“…In contrast to SiO x -covered SiNW-based devices, the insulating properties in the case of oxide-free SiNW-based devices are exclusively to be realized by the organic monolayer itself. One possibility to improve the monolayer quality is by using alkynes instead of alkenes (Sieval, 2000b;Faber, 2005a;Scheres, 2010). To conclude, selective functionalization of the nanowires is critical to retain sensitivity as the modification of the background oxide results in a reduced sensitivity.…”