Silicone Surfaces adsorption

Neyts EC, Khalilov U, Pourtois G, Van Duin ACT (2011) Hyperthermal oxygen interacting with silicon surfaces adsorption, implantation, and damage creation. J Phys Chem C 115(11) 4818 823... 

Flimpsel F J, McFeely F R, Morar J F, Taleb-lbrahimi A and Yarmoff J A 1990 Core level spectroscopy at silicon surfaces and interfaces Proc. Enrico Fermi School on Photoemission and Adsorption Spectroscopy and Interfaces with Synchrotron Radiation vo course CVIII, eds M Campagna and R Rose (Amsterdam Elsevier) p 203... 

On the atomic level, etching is composed of several steps diflfiision of the etch molecules to the surface, adsorption to the surface, subsequent reaction with the surface and, finally, removal of the reaction products. The third step, that of reaction between the etchant and the surface, is of considerable interest to the understanding of surface reactions on an atomic scale. In recent years, STM has given considerable insight into the nature of etching reactions at surfaces. The following discussion will focus on the etching of silicon surfaces [28]. 

In an effort to understand silicon surface diffusion, NoorBatcha, Raff and Thompson have employed molecular dynamics to model the motion of single silicon atoms on the Si(001) and Si(lll)surfaces. Morse functions are used for the pair forces, with the parameters being determined by the heat of sublimation. Because different forces were used for the diffusing and substrate atoms, the incorporation of gas-phase species into the crystal could not be directly modeled. Nonetheless, they were able to explore the characteristics of adsorption and diffusion for single atoms. 

Tokumoto, H., Miki, K., Murakami, H., Bando, H., Ono, M., and Kajimura, K. (1990). Real-time observation of oxygen and hydrogen adsorption on silicon surfaces by scanning tunneling microscopy. J. Vac. Sci. Technol. A8, 255-258. 

The amount of surface adsorption of a number of proteins ranging in molecular mass from 6.5 to 670 kDa and isoelectric point (pi) from 4.3 to 10.5 to several commonly used container surfaces (glass vials either untreated, siliconized, sulfur treated or Purcoat treated plastic vials polyester + 0.3%, polyester 5x0, PP, and nylon). A 5-mL volume of protein solution was added to each vial, yielding a surface-to-volume ratio of 2.4cm2/mL. No correlation was found between the amount adsorbed and the molecular mass or isoelectric point, although glass surfaces appeared to bind more protein under the experimental conditions examined [156]. 

In the following section, we provide a brief review of the structures of the major semiconductor surfaces for which the adsorption and reaction chemistry will be covered in this chapter. This includes the (100) and (111) crystal faces of silicon and germanium. Chapter 1 of this book also provides a brief overview of the structure of the silicon surface. The surface structures of compound semiconductors, including GaAs and InP, can be quite complex and are not covered here. A number of reviews describe the structure of these surfaces much more extensively [5,6,25-29], and the reader is referred to those references for more detail. 

The first examples of what can be categorized as [2 + 2] type cycloaddition product formed by reaction between an alkene and a silicon surface were reported in the late 1980s. Alkenes such as ethylene, as well as the related alkyne molecule acetylene, were reacted with the clean Si(100)-2 x 1 surface in vacuum [196-213]. The adsorption of these unsaturated C2 molecules (ethylene and acetylene) on Si(100)-2 x 1 is also discussed in Chapter 1. The alkenes were found to chemisorb at room temperature, forming stable species that bridge-bonded across the silicon dimers on the surface. The reaction proceeded by formation of two new a bonds between Si and C atoms, hence the bonding was referred to as di-sigma bonding. In addition, it was shown that while the bonds of the alkene and of the Si—Si dimer are... 

The slope is indicative of the type of release mechanism. A slope of 0.5 indicates a diffusion-controlled release a slope of 1.0 indicates that a corrosion-related mechanism is operable.The diffusion release mechanism is characterized by surface adsorption, ion exchange, and migration. Chemical corrosion, or alteration of the silicate lattice, is characterized by hydroxyl attack on silicon or by hydrogen attack on bridging oxygens. 

Ellipsometry can follow the interactions between two types of biological macromolecules, the first of those two bound physically to the surface, the other acting from the solution. The binding of conconavalin A to adsorbed mannan 180) and of cholera toxin to adsorbed ganglioside t83) are examples. The adsorption of complement factors to an antibody-coated surface was monitored by ellipsometry and a modification of the same method was used for quantification of migration inhibition of human polymorphonuclear leucocytes 182). Interaction of proteins and cells with affinity ligands covalently coupled to silicon surfaces has been also studied 183). 

The adsorption of block copolymers can be controlled by different stimuli, in particular by the pH since most of the brushes formed by block copolymers adsorption are polyelectrolyte brushes [129, 130], The group of Armes, for instance, studied the pH-controlled adsorption of a series of block copolymers [131, 132], In the case of copolymers bearing hydrophobic 2-(diethylamino)ethyl methacrylate groups (DEA) and a water-soluble zwiterionic poly(2-methacryloyl phosphoryl-choline) (MPC) block, they showed that at low pH the cationic DEA flatted to the anionic silicon surface while the MPC was in contact with the solution [132], At around neutral pH, micelles were formed in solution and adsorbed onto the surface because the DEA core was still weakly cationic. The MPC block formed the micelle coronas. Nevertheless, at higher pH the micelles became less cationic and the adsorption rate decreased. 

The simplest hydrocarbon molecule is acetylene HC=CH, which in vacuum possesses a triple carbon carbon bond. If this molecule attaches to a clean silicon surface, it has essentially two options it can either adsorb on the tip of a silicon dimer, where the C-C bond in this case is reduced to a double bond or it can attach to two adjacent dimers, if the C-C bond is reduced to a single bond. There was some controversy, a few years ago, about the preferred adsorption site. Different methods seemed to reach a different conclusion concerning the actual adsorption geometry under different thermal conditions (for an outline of the discussion, see [57]). There were essentially two diverging opinions (i) There are only two adsorption... 

As already mentioned, in the case of semiconductor surfaces there is often a strong surface rearrangement upon adsorption due to the covalent bonding of the semiconductor substrate. The benchmark system for the study of the adsorption and desorption dynamics at semiconductor surfaces is the interaction of hydrogen with silicon surfaces [2, 61]. Apart from the fundamental interest, this system is also of strong technological relevance for the growth and passivation of semiconductor devices. 

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