Laser Flash Evaporation

Chemical Vapor Deposition (CVD) and Chemical Vapor Synthesis (CVS) rely on the generation of a homogeneous mixture of reactants without condensation or preliminary decomposition. Typically, highly volatile precursors are delivered either directly as gas through mass flow controllers or by evaporation of a liquid in a bubbler and transport by an inert carrier gas to the reactor.

For many elements no precursors of high volatility exist which makes precursor delivery challenging. However, for most metallic elements (water free) beta-diketonates or acetates are available commercially in form of powders of low volatility. Most of these and related compounds absorb infrared radiation at the emission line of a CO2 laser (10.6 µm) which makes it possible to perform non-equilibrium Laser Flash Evaporation (LFE).

Benefits of LFE are

  • high evaporation rate even for alkaline earth and rare earth elements
  • no preliminary decomposition
  • evaporation of precursor mixtures of predefined composition enabling the generation of complex oxides such as perovskites or spinells with controlled stoichiometry
  • variation of evaporation time (pulsing) to control particle growth and film formation
  • J. Geiss, J. Schulte, and W. Winterer, Flash evaporation of low volatility solid precursors by a scanning infrared laser, J. Nanopart. Res. 24(2022) 248, 10pp.
  • I. Stijepovic, R. Djenadic, V. V. Srdic, M. Winterer, Chemical vapour synthesis of lanthanum gallium oxide nanoparticles, J. Europ. Ceram. Soc. 35 (2015), 3545-3552
  • R. Djenadic and M. Winterer, chapter 2, Chemical Vapor Synthess of Nanocrystalline Oxides, in Axel Lorke, Markus Winterer, Roland Schmechel, und Christof Schulz (eds.), Nanoparticles from the Gas Phase – Formation, Structure, Properties, Springer Berlin 2012, ISBN 978-3-642-28546-2
  • R. Djenadic, G. Akgul, K. Attenkofer, and M. Winterer, Chemical Vapor Synthesis and Structural Characterization of Nanocrystalline Zn1-xCoxO (x = 0-0.50) Particles by X-ray Diffraction and X-ray Absorption Spectroscopy, Journal of Physical Chemistry 114 (2010), 9207-9215
  • M. Winterer, V. Srdic, R. Djenadic, A. Kompch, T. E. Weirich, Chemical vapor synthesis of nanocrystalline perovskites using laser flash evaporation of low volatility solid precursors, Rev. Sci. Instr. 78 (2007), 133903, 5pp.