294 8 Surface processes in thin ®lm devices

Figure 8.21. High resolution TEM images of TaC particles in nanotubes where (a) the TaC particles are encapsulated at tips, and (b) graphite fringes suggest epitaxial growth on the particles (from Terrones et al. 1998, reproduced with permission).

®gure 8.21 with compositional analysis via EELS on the nanometer scale (Golberg et al. 1996, 1997). With this number of variables to explore, it seems only a matter of time before practical displays can be devised to rival those already demonstrated for the Spindt cathode and DLC geometries. But of course that does not mean that such a display will necessarily be successful in the marketplace, where it has to compete with all other ¯at display technologies as discussed earlier in section 6.2.2, and/or ®nd its own particular niche. The advantage is the high intrinsic brightness, which may make it suitable for projection onto a large screen; the list of potential disadvantages will distinguish optimists from pessimists.

Note that in the above two examples the distinction between surfaces, thin ®lms and molecules has all but disappeared: the molecule is all surface and is the thin ®lm. What we are seeing here is an important stage in the development of single molecule electronics. The next stage is again the transition to manufacturing, which may well be a rocky road, and test to the limit who is serious. As they say on TV: `don't go away', or equivalently `watch this space'!

8.4.4Combinatorial materials development and analysis

The combination of step-wise thin ®lm deposition processes with analysis on a microscopic scale is coming to be known as combinatorial materials development. This series of techniques uses automated deposition and annealing sequences to produce a series of diVerent compositions, thicknesses and/or doping levels in a matrix pattern of dots