Thermal Stability of the Modified Surfaces

It seems that no thorough and systematic studies on the thermal stability of Si smfaces modified via Si-N linkages have been performed, so that up to now, still little is imder-stood about the corresponding thermal desorption reaction mechanisms. However, some scarce results are available. 

The case of nitrobenzene anchored to H-terminated (100) Si surfaces through cyclo-condensation reaction of nitrobenzene at 473 K (-200 °C) was studied by Perrine et al. [215]. The cyclocondensation reaction results in the presence of three surface species, which are the nitrosoadduct [ t N(Si)0(Si)] as the main component, followed by the phenylnitrene adduct (ONSi ) and a stable intermediate as the minor species. After an annealing treatment to 823 K (-550 °C) for 30 s, the concentration of phenylnitrene substantially increases, whereas the other two species decrease slightly, but the nitrosoadduct remains the major product. This observation suggests that those species undergo a conversion into phenylnitrene adducts. The fact that all the three components are still present upon this annealing treatment indicates that they are thermally stable at this temperature. 

To the best of our knowledge, no data are available about the thermal stability of H-terminated Si surfaces grafted with azido groups. However, the thermal stability study of the Si surfaces terminated by the simplest azido group, i.e., N, would be of high interest for further modifications for instance in the context of biodevice systems. It would be helpful for xmderstanding the mechanisms of surface reactions as well as for reaching a finer control of the surface at the atomic level. 

Linkage Monolayer name Formula Substrate T ( C) Conditions Mechanism Ref. 

Dusciac, V. Brize, J.-N. Chazalviel, Y.-F. Lai, H. Roussel, S. Blonkowski, R. Schafranek, A. Klein, C. Henry de Villeneuve, P. Allongue, E Ozanam, and C. Dubourdieu, Chemistry 

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In all cases, IR spectra are consistent with the attachment of a methylsllane in accordance to equation 1. Proof of chemical bonding lies in the thermal stability of the modified surfaces prolonged heating (150°C) under vacuum causes little to no decrease of the methyl C-H or Si-C bands. 

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