Films grain size

As nicely shown by Puddephatt and coworkers, the complexes Ag(hfac)(PR3) and Ag(fod)(PR3) (R = Me, Et) are excellent CVD precursors for deposition of smooth pure silver films (grain size 0.1-0.25 p,m) using moisf hydrogen as carrier gas, as could be... 

Diffusion into and through a material is by bulk diffusion, grain boundary diffusion, and/or surface diffusion in order of increasing diffusion rates. Thin films are often used as diffusion barriers. Since in thin films, grain size is typically small compared to bulk materials, the grain boundary mechanism may dominate. However, if there is a columnar microstructure, surface diffusion may predominate. Amorphous films seem to be particularly good diffusion barrier materials since they have no grain boundaries. 

Figure 11.6 (a) SEM image of a nanostructured Ti02 film (grain size 40 nm). 

Columnar Structure and Grain Size. Most of the deposited films reported in the Hterature have a so-called columnar stmcture (see Fig. 

X-ray Diffraction (XRD) is a powerful technique used to uniquely identify the crystalline phases present in materials and to measure the structural properties (strain state, grain size, epitaxy, phase composition, preferred orientation, and defect structure) of these phases. XRD is also used to determine the thickness of thin films and multilayers, and atomic arrangements in amorphous materials (including polymers) and at inter ces. 

Grain size in textured films. For films having a preferred growth direction—e.g., (111)—LEED can be used to determine the preferred direction and the grain size parallel to the surfrce. The preferred direction is obtained from the symmetry of the diffraction patterns, while the grain size is obtained from the shape in angle of diffracted beams. 

Figure 5 Atomic force microscope images of an aluminum film deposited on ambient (a) and heated (b) Si substrates. The scales are 15 pm x 15 pm (a) and 20 pm x 20 pm (b). The grain size can be clearly observed (Courtesy of M. Lawrence A. Dass, Intel Corporation).

Figure 5-24. u) Polar represenlalion (Irom —90 io +90 ) lor lire angular dependence ol lliioreseenee anisotropy (ll-V) in Th films willi grain sizes of 1500 mil (open squares). 000 nm (filled circles), and 200 nm (open circles), b) The angular dependence of electroluminescence anisotropy (H-V) measured from the LED contacted pari of the same samples. 

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