Radical-surface interactions silicon

Dimitrios Maroudas, Modeling of Radical-Surface Interactions in the Plasma-Enhanced Chemical Vapor Deposition of Silicon Thin Films Sanat Kumar, M. Antonio Floriano, and Athanassiors Z. Panagiotopoulos, Nanostructured Formation and Phase Separation in Surfactant Solutions Stanley I. Sandler, Amadeu K. Sum, and Shiang-Tai Lin, Some Chemical Engineering Applications of Quantum Chemical Calculations... 

Dimitries Maroudas, Modeling of Radical-Surface Interactions in the Plasma-Enhanced Chemical Vapor Deposition of Silicon Thin Films... 

Maroudas, D., Modeling of radical-surface interactions in the plasma-enhanced chemical vapor deposition of silicon thin films, in (A.K. Chakraborty, Ed.), Molecular Modeling and Theory in Chemical Engineering , vol. 28, p. 252. Academic Press, New York (2001). Maroudas, D. Multiscale modeling, Challenges for the chemical sciences in the 21st century Information and communications report , National Academies, Washington, DC. p. 133. 

Maroudas, D. Modeling of radical-surface interactions in the plasma-enhanced chemical vapor deposition of silicon thin films. In Molecular Modeling and Theory in Chemical Engineering Chakraborty, A.K., Ed. Academic Press New York, 2001 252-296. 

MODELING OF RADICAL-SURFACE INTERACTIONS IN THE PLASMA-ENHANCED CHEMICAL VAPOR DEPOSITION OF SILICON THIN FILMS... 

B. Interactions of Si I F Radicals with Crystalline Silicon Surfaces... 

A sticking model is used for the plasma-wall interaction [137]. In this model each neutral particle has a certain surface reaction coefficient, which specifies the probability that the neutral reacts at the surface when hitting it. In case of a surface reaction two events may occur. The first event is sticking, which in the case of a silicon-containing neutral leads to deposition. The second event is recombination, in which the radical recombines with a hydrogen atom at the wall and is reflected back into the discharge. 

The difference in reactivity was also found for the paramagnetic surface defects -(=Si-0-)3Si radicals [16]. Since the observed effects are due to the difference in the structure of the nearest environment of the surface silicon atom, it is most pronounced when this atom acts as an active site. This difference should cease with an increase in the number of chemical bonds that separate the active site and surface silicon atom of the solid with which it is linked. They are almost absent for the (=Si-0-)3Si-CFl2- CF[2 radical in which the active site is localized on the terminal carbon atom [16]. For this reason, it is desirable to have a probe in the immediate contact with a lattice silicon atom. The Si-H group fits best these requirements. Such groups can be obtained upon the interaction of the silyl-type radicals with the hydrogen or deuterium molecules (cf. Section 6.3). The IR band due to the stretching vibrations of the Si-Fl bonds obtained upon the hydrogenation of silyl radicals ... 

Past kinetic studies show that coadsorbed reactants on the silicon surface, methylchloride, methyl radicals and chlorine radicals compete with products for surface sites, but much is still unknown about these surface chemical processes. This reaction is carried out at elevated pressures so conventional high vacuum surface science and techniques cannot be used to uncover details of the reaction path. To circumvent this problem. Bent [1] and co-workers have developed low temperature techniques which permit direct observation of the interactions of reactants and products with the silicon surface. This type of understanding is key to continuous improvement of the Direct Process. 

The reduction current on p-Si is small in the dark because it is limited by reaction (6.14), which requires electrons. On the active surface the reaction scheme is more complex due to the interaction between silicon radical and hydrogen peroxide generating a -OH radical ... 

The surface of FPS is characterized by the presence of at least three dominant types of groups hydrophobic hydrocarbon radicals R bonded to silicon atoms, often containing electron-donating or electron-accepting groups residual silanol groups, =Si-OH, where the polymer chain terminates oxygen atoms of siloxane bonds, =Si-0-Si=. Such a variety of the surface character allows for interactions with different sorbates ... 

Fig. 2. Two-dimensional illustration of the geometric definition of the pore size distribution [25]. Point Z may be overlapped by all three circles of differing radii, whereas point Y is accessible only to the two smaller circles and point X is excluded from all but the smallest circle. The geometric pore size distribution is obtained by determining the size of the largest circle that can overlap each point in the pore volume. (Reproduced with permission from S. Ramalingam, D. Maroudas. and E. S. Aydil. Interactions of SiH radicals with silicon surfaces An atomic-scale simulation study. Journal of Applied Physics, 1998 84 3895-3911. Copyright 1998, American Institute of Physics.)...

D. Maroudas, and E. S. Aydil. Atomistic simulation study of the interactions of SiHj radicals with silicon surfaces. Journal of Applied Physics, 1999 86 2872-2888. Copyright 1999. American Institute of Physics.)... 

The detailed interactions between the SiH radicals and silicon surfaces can be captured by MD simulations of radical impingement at a grid of locations on the surface with varying radical molecular orientation with respect to the surface. Tlie reactions of SiH with the pristine Si(001)-(2 x 1) surface can be classified broadly into two classes (Ramahngam et al., 1998b). The radical either adsorbs dissociatively onto the surface or penetrates below the top surface layer into the substrate also resulting in dissociation. The H atom that is released upon radical dissociation becomes an interstitial impurity of the substrate Si lattice and it can migrate rapidly or channel deeper into the substrate. These reactions can be represented as... 

Ramalingam, S., Mahalingam, P, Aydil, E. S., and Maroudas, D., Theoretical study of the interactions of SiH2 radicals with silicon surfaces. J. Appl. Phys. 86, 5497-5508 (1999c). 

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