Investigation of molecule chemisorption on Si(001)2 × 1 surfaces by surface reflectance spectroscopies

Abstract

Several examples are given on the investigation of adsorption of atoms and molecules on Si(001)2 × 1 in ultra-high vacuum, by means of two different surface optical spectroscopies, the Surface Differential Reflectance Spectroscopy and the Reflectance Anisotropy Spectroscopy. Hydrogen, water, oxygen, benzene and pyridine adsorptions are presented. Specific spectra are obtained, which are interpreted as a function of the mode of adsorption of the adsorbates. In particular, it is possible to discriminate between adsorption on the dangling bonds of the Si dimers and adsorption inducing a breaking of the dimers. Moreover, quantitative information is obtained from these optical techniques which yields the determination of the absolute number of surface Si atoms involved in the bonding.

Reflectance-anisotropy spectroscopy and surface differential reflectance spectra at the Si(100) surface: Combined experimental and theoretical study

“…2. This spectrum is similar in shape and in amplitude to previous experiments performed on nominal samples, prepared either by the same procedure 21,25,26 or by applying a strain at the surface. 19 We have checked using low-energy electron diffraction ͑LEED͒ that the surface is not purely 2 ϫ 1 single domain and that non-negligible 1 ϫ 2 minority domains are present.…”

“…The basic pressure was 5 ϫ 10 −11 mbar and the maximum pressure did not exceed 5 ϫ 10 −10 mbar during the preparation. This procedure has been shown to favor the electromigration of atoms at the surface and to yield the formation of numerous broad terraces, hundreds of nanometers wide in average, 21,25,26 all having the same orientation. Importantly, with this technique, the number of double steps is relatively small and does not influence the optical response of the surface.…”

“…In particular, in the case of vicinal ͑100͒ surfaces, where the terraces are only 3.9 nm wide in average, this transition is strongly smoothed out and is almost not visible. 21,26 The I-QP spectrum ͑blue solid curve͒ calculated for the 2 ϫ 1 reconstruction displays a minimum at 2.7 eV, which becomes more intense and is shifted to 2.5 eV when the excitonic effects at the BSE level are included in the calculation ͑see red dashed curve͒. This negative peak is not present in the experimental spectrum.…”

RAS: An efficient probe to characterize Si(001)-(2×1) surfaces

“…On the vicinal surface spectrum, the total amplitude of the anisotropy reaches 4.2 · 10 À3 which is a larger anisotropy than presented in other studies [12,13,16,18]. The nominal silicon spectrum is similar to spectra obtained by Shioda et al [18,20]. The origin of the different features observed in the spectrum corresponding to the clean vicinal Si(0 0 1)-(2 · 1) surface, have been tentatively interpreted by using ab initio calculations [14].…”

Chemical manipulation of multifunctional hydrocarbons on silicon surfaces

“…In the case of germanium, the aromaticity of the pyridine ring is retained. The binding of pyridine between the two adjacent dimers of the Si(100)-2×1 surface is also in a general agreement with the Surface Differential Reflectance Spectroscopy studies [347,348]. Finally, Miwa et al [252] performed a set of molecularly resolved STM studies of pyridine on Si(100)-2×1 at room temperature.…”