Deposition and charactetization of coatings by Molecular Layer Deposition
Martin Seiler
Advanced Materials Science
11:15 - 12:15 Wednesday 20 November 2019 PH 01 150 Polycrystalline ZnO has already covered a wide range of applications for over 100 years, leading from facial powders, sunscreens and lubricant additives to catalysts, transparent conducting electrodes and piezoelectric transducers. The renewed interest is due to improvements in growth technologies for high quality films and furthermore since the difficulties in fabricating a p-type ZnO are being overcome.
The aim of this thesis is to produce a metal-organic hybrid film, in this case a Zincone film, with different combinations of organic precursors by molecular layer deposition and from there achieve a porous crystalline ZnO thin film. As seen in nature porous solids can be fundamental for structural and functional purposes. By being able to engineer size, shape, connectivity, directionality and quantity of pores not only the performance of already existing applications can be extremely improved but also new ones are explored. When tuning the porosity down to the nanometer range a dramatic enhancement of the accessible surface area is achieved which makes of a porous material a perfect candidate in sensing, optics, microelectronics, energy materials, water treatment and more. The technological growth is confirmed by an increased scientific interest in developing porous solids.
Molecular layer deposition (MLD) is a self-limiting process in which a substrate is alternatingly exposed to different reactive precursor gases which react on the surface and build up layers (Figure 1). As the precursors only react with the surface it is possible to deposit a film with alternating metallic and organic monolayers which allows an extremely precise control over the thickness. Furthermore, with MLD a conformal coating of very complex 3-D structures is possible. The obtained Zincone film is then heated up to remove the organic part and to trigger a crystallization of the leftover ZnO. To show the practical applicability the photocatalytic efficiency of the porous ZnO is measured by the decomposition of a dye.
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Institute of Solid State Physics
