Deposition of Thin Dye Coatings by Glow Discharge Induced Sublimation

Abstract

A novel method for the vacuum deposition of thin fluorescent dye coatings by means of glow discharge induced sublimation (GDS) is disclosed. Powdered organic compound is put on a radio frequency plasma sputtering source and bombarded by low energy (<1 keV) noble gas ions and electrons. Ion bombardment gives rise to a local heating which induces sublimation of the dye molecules. The method has been successfully used for deposition of 3-hydroxyflavone (3-HF) coatings on silicon substrates. Plasma diagnostics, as performed by means of mass spectrometry and in situ optical emission spectroscopy, point out both the sublimation of integer 3-HF molecules and the presence of 3-HF molecular fragments in the glow discharge. The integer 3-HF molecules are positively ionized or protonated before reaching the substrate. Rutherford backscattering spectrometry and elastic recoil detection analysis confirm that the deposited film is stoichiometric within the experimental errors. FT-IR analysis points out all the main cha...