Optical properties thin gold films

Transparent conductive coatings combine high optical transmission with good electrical conductivity. The existence of both properties in the same material is, from the physics point of view, not trivial and is only possible with certain semi-conductors like indium oxide, tin oxide, cadmium oxide, and with thin gold and silver films, e.g. [157]. Particularly antimony or fluorine doped tin oxide (ATO, FTO), tin doped indium oxide (ITO), and aluminium, indium, or boron doped zinc oxide (AZO, IZO, BZO) are of technical importance [157a]. 

It is claimed to be able to measure thicknesses with an accuracy of about 0.3 A, approximately the thickness of an atomic layer. Because the method relies on polarized fight, ellipsometry is a nondestructive technique, which makes it suitable for in situ measurements in some cases. One disadvantage is that the substrate must be reflective, so gold or sUicon wafer is often used. However, a major disadvantage with the technique is interpretinging the data, which is not trivial models of the air—thin film-substrate must be used. The dielectric and optical properties of the thin film must be known accurately to calculate the thickness of the film, and even then the modelling usually assumes a homogeneous layer which may not always be justified. 

We have carried out an investigation of the electrical and electro-optical properties of a series of Schottky barrier diodes fabricated with polyacetylene sandwiched between two metal contact layers, one to form the Schottky barrier and the other (gold) to provide an ohmic contact [56]. This type of structure is straightforward to fabricate with an extrinsically-doped semiconductor and there have been several reports of such devices which use polyacetylene or other conjugated polymers [57-62]. The details of the device fabrication have been given in section 3.2, and we show in figure 10 the details of the typical structures that we have used for this work. We have worked with relatively thick films of polyacetylene, in the range 500 - 1(XX) nm, so as to avoid the possibility of short-circuits tetween top and bottom electrode, but we have kept the metal contact layers thin so that they are semi-transparent and allow optical transmission measurements. 

R.R. Zito, W.S. Bickel, W.M. Bailey, The physical and optical properties of agglomerated gold films. Thin Solid Films 114 (1984) 241. 

D. J. ScHiEERiN, Self-assembled gold nanoparticle thin films with nonmetal-lic optical and electronic properties. Langmuir 1998, 14, 5425-5429. 

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