Chemical vapour deposition devices

MS Weaver and DDC Bradley, Organic electroluminescence devices fabricated with chemical vapour deposited films, Synth. Met., 83 61-66, 1996. 

Recently, low-temperature routes have been sought for by decomposition of organometallic complexes with tellurium-containing ligands. The optoelectronic devices normally require the material to be used as thin films. They are fabricated with special methods, such as molecular beam epitaxy, metal-organic chemical vapour deposition, or atomic layer deposition. 

Figure 26.14 FETs based on SWCNT networks (a) Atomic Force Microscope (AFM) amplitude image of a network of tubes grown by chemical vapour deposition. (b) Gate dependence of conductance of such a network before and after selective ECM. Fjj is 10 mV before and 100 mV after ECM. (c) Variation of conductance of the same device after spotting two different solid polymer electrolytes and using an electrode in contact with the SPE as the gate (F s = 100 mV). The composition of the SPE is identical to that in Figure 26.9. Fpeg is the voltage applied to the polymer electrolyte-gate.

We devote a significant part of this chapter to the method of chemical vapour deposition, the development of which has been closely tied to the need to deposit thin films of a range of metals and inorganic materials for use in semiconducting devices, ceramic coatings and electrochromic materials. Table 27.3 lists some applications of selected thin film materials. Part of the challenge of the successful production of thin films is to find suitable molecular precursors, and there is much research interest in this area. 

Although the vast majority of known metallophosphorus complexes remain of academic interest only, a few have well-established uses of great importance. These are mainly in the fields of catalysts and medicinals where interest and development continues unabated. Among the smaller but nevertheless growing applications are in chemical vapour deposition, chemical synthesis and various electrical devices. 

In Takahashi et al. (2005) a suspended MEMS based micro-fuel reformer was designed and manufactured, and the performance of the reformer evaluated. In this study, in-situ chemical vapour deposition (CVD) of the alumina catalyst bed on a membrane was used as the preparation method for better mechanical and thermal isolation of the reaction zone on the membrane. Most of the microfabricated Pd-based MMs are much more efficient than the conventional thicker or large scale devices, as reported by many authors. 

Spin coating is one of the simplest techniques for applying thin films, but it is no use for low solubility polymers (HaU et aL, 1998). Chemical vapour deposition solves this problem because monomers are delivered to the surface in the vapour phase, eliminating the need to dissolve macromolecules. They then undergo simultaneous polymerization, resulting in the formation of a thin film. Moreover, the substrate compatibility obtained using this method is excellent for biomedical devices such as implants, membranes and microfluidic devices (Asatekin et al., 2010). 

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