Chemistry Reference
In-Depth Information
can be contaminated by metallic, organic, and ceramic species. For example, an as-
received silicon wafer typically has several thousand ceramic particles and metal con-
for Fe, Ni, Cu, and Zn.
131,488
Figure 2.9 schematically
illustrates a possible surface condition of a silicon electrode.
Thus, unless in a vacuum, the surface of silicon is never “clean” because of the
adsorption by foreign species. As will be seen in the following sections, the type of ter-
mination, in terms of chemical nature, thickness, and composition, is a function of how
the surface is prepared and cleaned. In particular, the surface cleaned with HF solu-
tions, which are widely used for preparation of silicon surfaces, is known to be hydro-
gen terminated. On the other hand, in water and non-HF solutions, silicon surfaces tend
to be covered with an oxide film. Employing certain treatment processes, the surface
of silicon can be terminated by different species—H and/or F and/or OH—using dif-
ferent cleaning solutions as shown in Table 2.7.
126
centrations of
