Atomic-level flatness

Etching in HF-containing solutions is particularly important as they are involved in almost all cleaning processes for silicon surfaces. It is often the last cleaning step in surface preparation for further processing. The silicon surface that is treated with HF solution is terminated by hydrogen (see Chapter 2). The atomic level flatness is related... 

Using the same Hypercarb colunm and eluents, Macko et al. have shown a separation of ethylene copolymers by the level of comonomer incorporation [114, 115]. Similar results were obtained by Miller et al. [116] on the same Hypercarb colunm. The presence of branches in the ethylene copolymers reduces the adsorption potential on the atomic level flat surface of graphite and a linear correlation is obtained between the comonomer mole percentage incorporated and the elution volume, as shown in Fig. 31 for various types of copolymers. 

The line sections analysis of the flat parts of the copper surfaces is shown in Fig. 12. The roughness of the flat parts of the copper surface, polished both mechanically and electrochemically, is very small and less than the atomic diameter of copper. For this reason, it can be said that these flat parts of the surface are smooth on the atomic level. The roughness of the flat parts of the copper surface, only polished mechanically, is less than 2 atomic diameters of copper.12... 

Reflection analysis of a silver mirror surface taken as a reference standard showed that the reflection of light from this surface is mostly mirror reflection and that the degrees of mirror reflection are very close to the ideal reflectance of silver. The structural characteristics of this surface, which provide a high degree of mirror reflection, are flat and mutually parallel parts which are smooth on the atomic level, with adjacent flat parts being separated by several atomic diameters of silver. 

Hence, the conditions which must be fulfilled in order for metal surfaces to be mirror bright are (i) flat parts of the surface which are smooth on the atomic level and (ii) distances between adjacent flat parts are comparable with the distances between the adjacent flat parts of a silver mirror. 

High-resolution scanning probe microscopy (SPM) studies require flat surfaces at an atomic level. The preparation of flat surfaces is essential and is not a minor problem. This necessitates advanced understanding of surface reactivity and chemistry success has been obtained with silicon because systematic ex-situ studies of surface topography have been conducted by several groups. A good surface preparation is certainly more difficult with compound semiconductors because the different elements may dissolve at different rates. 

It has been known for many years that surface-free energies of flat solid substrates are determined by atomic-level constitutions of their outermost surfaces as a result, alterations of chemical structures of outermost monoraolecular layers by external stimuli—including pH changes, heat application, photoirradiation, and so on—lead to the modification of versatile interfacial phenomena. Photoirradidation seems to be the most convenient way to manipulate surface properties because of its ability to control them precisely in time and space. In fact, there have been a number of reports... 

All results were analyzed with the help of the G-C-S model for the interfacial region, although for this model the surface is assumed to be flat down to an atomic level and its atomic arrangement is not taken into consideration. This last parameter should be a crucial one in the model of this region. 

Although Eqs. (12.4) to (12.6) elucidate the nature of the driving force operative during creep, they do not shed any light on how the process occurs at the atomic level. To do that, one has to go one step further and explore the effect of applied stresses on vacancy concentrations. For the sake of simplicity, the following discussion assumes creep is occurring in a pure elemental solid. The complications that arise from ambipolar diffusion in ionic compounds are discussed later. The equilibrium concentration of vacancies Cq under a flat and stress-free surface is given by (Chap. 6)... 

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