Infrared spectroscopy is used to study the etching process of stepped Si(111)9° surfaces as a function of the pH of the etching HF solutions. This process results in complete H termination of the silicon surface, including terraces, steps, and defects; the surface structure can therefore be well studied using infrared (IR) spectroscopy. Polarized IR absorption spectra of the Si–H stretching vibrations (i.e., in the region 2060–2150 cm−1) vary dramatically as the pH of the etching solutions increases from 2.0 to 7.8. In general, higher pH solutions yield sharper bands and more easily assigned spectra, making it possible to identify the step and terrace species and thus to infer the surface structure and step morphology (i.e., to investigate the etching process). The data are explained by a model involving different etching rates for each individual surface species: The highest rate of removal is for isolated adatom defects located on (111) planes and the lowest is for the ideally H‐terminated (111) planes ...

Chemical etching of vicinal Si(111): Dependence of the surface structure and the hydrogen termination on the pH of the etching solutions

Hydrogen interaction with clean and modified silicon surfaces

This article focuses on recent scanning tunnelling microscopy studies that have led to an improved understanding of the interaction of hydrogen with silicon surfaces. The structure and bonding of the Si(111)-7 × 7 and Si(100)-2 × 1 surfaces are described together with the adsorption and desorption of hydrogen from these surfaces. The role of hydrogen in the passivation of silicon surfaces and silicon chemical vapour deposition are also discussed.

Scanning tunnelling microscopy of the interaction of hydrogen with silicon surfaces

The importance of structure and bonding in semiconductor surface chemistry: hydrogen on the Si(111)-7 × 7 surface

In situ attenuated total reflection Fourier transform infrared spectroscopy was used to study the H bonding on the surfaces of a-Si:H and nc-Si:H during plasma enhanced chemical vapor deposition from SiH4/H2/Ar containing discharges. Well-resolved SiHx (1⩽x⩽3) absorption lines that correspond to the vibrational frequencies commonly associated with surface silicon hydrides were detected. During deposition of a-Si:H films using SiH4 without H2 dilution, the surface coverage was primarily di- and trihydrides, and there are very few dangling bonds on the surface. In contrast, during deposition of nc-Si:H using SiH4 diluted with H2, the amount of di- and trihydrides on the surface is drastically reduced and monohydrides dominate the surface. Furthermore, the vibrational frequencies of the monohydrides on nc-Si:H film surfaces match well with the resonant frequencies of monohydrides on H terminated Si (111) and Si (100) surfaces. The decrease of higher hydrides on the surface upon H2 dilution is attributed to i...

Silicon hydride composition of plasma-deposited hydrogenated amorphous and nanocrystalline silicon films and surfaces

Multiple internal reflection (MIR) infrared spectroscopy has been used to study the adsorption of hydrogen on the Si(111)‐7×7 surface over the temperature range of 100–400 K. The high resolution of this technique has enabled us to observe three different silicon monohydride stretch modes at 2076, 2086, and 2095 cm−1. Using the polarization selection rules for infrared spectroscopy we have assigned these modes to a silicon monohydride whose bond axis is parallel to the surface normal and two monohydrides whose bond axes are tilted with respect to the surface normal. We have also observed the temperature dependent formation of surface dihydride and trihydride species. The formation of both the dihydride, observed at 2119 cm−1, and the trihydride, seen at 2143 cm−1, is favored by low adsorption temperatures. Finally, we also report a temperature dependent competitive formation between the two higher hydrides with the formation of the dihydride species maximizing near 200 K and lower temperatures favoring the...

K. J. Uram

Papers

The adsorption of hydrogen on Si(111)‐7×7 as studied by multiple internal reflection spectroscopy