Thin films by Electrospray and Pressurized Spray Deposition
Yttria-stabilized zirconia (YSZ) films (< 1 um thickness) were deposited on hot substrates by electrostatic and pressurized atomization. Droplet transport and evaporation are examined with a Phase Doppler Anemometer while the film morphology and composition are investigated by Scanning Electron Microscopy and Energy Dispersive X-ray Analysis. The effects of spraying configuration, solvent/ precursor composition and substrate temperature on the resulting film morphology are examined. Smooth and dense YSZ films can be made at substrate temperatures above the solvent boiling point while precursor influence is negligible. Furthermore, the spray droplet has to reach the substrate without solid precipitation in the droplet or complete evaporation of the solvent. A deposition diagram for film texture was developed as function of droplet size, precursor concentration and substrate temperature using a theoretical model for electrospray droplet transport and evaporation.
Nano-particulate copper and indium metal layers of 1-2 um have been deposited by non-vacuum techniques such as doctor blade, screen printing and electrospray using alcoholic suspension pastes. Electrospray showed a high efficiency of material usage and yielded the most uniform morphology. The metal precursor layers were subjected to a thermal treatment (500-600 degreesC) in selenium vapor to convert the porous metal layers into CuInSe2 compound layers. The chemical conversion, investigated by X-ray diffraction, showed the presence of the In2O3 impurity phase in the precursor as well as in the selenized layers.
Recent relevant publications:
- O. Wilhelm, S.E. Pratsinis, D. Perednis, L.J. Gauckler, ”Electrospray and pressurized spray deposition of yttria-stabilized zirconia films”, Thin Solid Films, 479, 121-129 (2005).
- D. Perednis, O. Wilhelm, S.E. Pratsinis, L.J. Gauckler, ”Morphology and deposition of thin yttria-stabilized zirconia films using spray pyrolysis”, Thin Solid Films, 474, 84-95 (2005).
- M. Kaelin, H. Zogg, A.N. Tiwari, O. Wilhelm, S.E. Pratsinis, T. Meyer “Electrosprayed and Selenized Cu/In Metal Particle Films“, Thin Solid Films, 457, 391-396 (2004).
- O. Wilhelm, L. Maedler, S.E. Pratsinis, ”Electrospray Evaporation and Deposition”, J. Aerosol Sci., 34, 815-836 (2003).