Sihcon surfaces

The distribution of impurities over a flat sihcon surface can be measured by autoradiography or by scanning the surface using any of the methods appropriate for trace impurity detection (see Trace and residue analysis). Depth measurements can be made by combining any of the above measurements with the repeated removal of thin layers of sihcon, either by wet etching, plasma etching, or sputtering. Care must be taken, however, to ensure that the material removal method does not contaminate the sihcon surface. 

Studies on fluoro-fiillerenes (CeoFx) were recently undertaken because of the interest in such materials as cathodes in Li batteries. A recent HREELS-based work focused on the interaction between CeoFx and the sihcon surface. The spectrum of CeoFx thin layers deposited on Si(lll)-(7 x 7) revealed a weak but well-defined loss feature at 107 meV. This peak was attributed to a Si-F stretch mode, which imphed... 

A peak similar to that shown in Fig. 2.25 is observed on a sihcon surface with about 40 A of thermally grown oxide and the peak becomes higher and broader with additional anodic thickening. The apparent density depends on light intensity and on whether the sample is biased cathodicahy or anodically before the measurement This capacitance peak, however, disappears almost completely in the presence of HF, which dissolves silicon oxide. Thus, the surface states of a silicon electrode in KCl solution, according to Madou et are physically associated with the unsaturated bonds at the Si/Si02 interface. On the other hand, in similar solutions, Chazalviel °° found that surface states, situated at about 0.9eV below the conduction band, are caused by the adsorbed ions but not the oxide. Thus, for an oxide-covered electrode (e.g., 12nm... 

The silicon surface can be stabilized using surface modification techniques which are divided into three categories (1) attachment of redox mediator which consumes the holes on the surface (2) attachment of electronically conducting polymer and (3) coating with thin metal or semiconducting films to create a buried semiconductor interface. Combinations of these approaches can also be used to stabilize the sihcon surface. ... 

Figure 6.29 shows, as an example, the effect of surface modification on the sta-bihty of sihcon electrode in an aqueous solution. The bare sihcon surface is quickly passivated in aqueous solution under illumination. Coating the electrode with a layer of either ferrocene or polypyrrole gives an improvement in the stabihty. The stability is further improved by a two-layer coating of ferrocene/polypyrrole as shown in Fig. 6.29. 

Hochbauer, T., Misra, A., Verda, R., Nastasi, M., Mayer, J.W., Zheng, Y., Lau, S.S. Hydrogen-implantation induced sihcon surface layer exfoliation. Phil Mag. B 80, 1921 (2000)... 

T.G. Stange, R. Mathews, D.F. Evans, and W.A. Hendrickson, Scanning tunneling microscopy and atomic force microscopy characterization of polystyrene spin coated onto sihcon surfaces, Lang muir 8, 920 (1992). 

Paruchuri, V. K, Fa, K., Moudgil, B. M., Miller, J. D. (2005,) Adsorption density of spherical cetyltrimethylammonium bromide (CTAB) micelles at a sihca/sihcon surface. Appl. Spectrosc. 59, 668-672. 

Rumpf K, Granitzer P, Albu M et al (2010) Electrochemically fabricated silicon/metal hybrid nanosystem with tailored magnetic properties. Electrochem Solid-State Lett 13 K15-K18 Santinacci L, Djenizian T, Hildebrand H et al (2003) Selective palladium electrochemical deposition onto AFM-scratched sihcon surfaces. Electrochim Acta 48 3123-3130 Sasano J, Schmuki P, Sakka T et al (2003) Laser-assisted nickel deposition onto porous silicon. Phys Status Solidi A 197 46-50... 

Koynov S, Brandt MS, Srutzmann M (2006) Black non-reflecting sihcon surfaces for solar cells. Appl Phys Lett 88 203107(1)-203107(3)... 

Li L-G, Liu S-M, Yo X-L, Hossu M, Jiang K, Chen W, Wag Z-G (2012) Formation mechanism and characterization of black sihcon surface by a single-step wet-chemical process. J Nanosci Nanotechnol 12(5) 3954-3958... 

Li H-F, Han H-M, Wu Y-G, Xiao S-J (2010) Biological functionalization and patterning of porous silicon prepared by Pt-assisted chemical etching. Appl Surf Sci 256 4048—4051 Linford MR, Chidsey CED (1993) Alkyl monolayers covalently bonded to sihcon surfaces. J Am Chem Soc 115 12631-12632... 

With increase of H2 percentage in the feed gas mixture over the range 0-40 % the fraction of silicon wafer occupied by radicals CF2 rises proportionally with the concentration of H2 (see Fig. 2) and riches the value 0.98797 at 40 % Ff2- The fraction of silicon surface covered by radicals CF3 not exceeds the value 0.01563, which is reached at 25 % H2 and in further calculations may not take into account. Starting with 40 % addition H2 the aU sihcon surface becomes passive because of the intensive adsorption of radicals CF2, CF3 for which CF2 + cfz = 0.99061. On the contrary in CF4 /O2 system the fractions CF2 and cFs beginning from 5 % O2... 

Okada, T., Ikada, Y. Modification of sihcone surface by graft polymerization of acrylamide with corona discharge. Makromol. Chem. 192(8), 1705-1713 (1991)... 

It is important to review properties of sihcon surfaces and the sample preparation in experiments, because this information is necessary input for modeling the peptide-Si(lOO) interface. In these experiments [275,276], the Si(lOO) surfaces were first cleaned in a solution of ammonium fluoride (NH4F) and hydrofluoric acid (HF) and then the adsorption experiments were performed in distilled water. This standard procedure ensures that the Si surface is widely free of oxide, which causes strong hydrophobic properties [359,361], The initial Si-F bonds after etching are replaced by Si H bonds in the rinsing process in de-ionized water. Although the oxidation proceeds also in water [361,362], it was found that the hydrophobicity of the Si samples is widely sustained during the peptide adsorption process. 

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