NOVELTY - Preparing a deposition on a substrate involves providing an ionic liquid comprising a precursor material for the deposition; vaporizing the precursor material from the ionic liquid; and depositing the precursor material on the substrate.    USE - For preparing a deposition on a substrate i.e. silicon-based substrates or metallic substrates (preferably Si, SiO2, stainless steel, and Al), ceramic substrates, glass or glass substrates and polymer substrates; and for manufacturing an electronic or optoelectronic device (claimed). Also useful in the semiconductor industry, glass industry and for making hard coatings such as aluminum oxide coatings, coatings on glass for solar cell applications, anti-reflection coatings, low-emissive coatings, hard coatings on tools for increased durability and lifetime, low-epsilon coatings, and metallization coatings; and in tools, glass windows, photovoltaics, light emitting diodes such as organic light emitting diodes and integrated circuits.    ADVANTAGE - The method provides an efficient precursor delivery system that can deliver a large vapor flow of precursor material to vapor deposition processes, where the vapor flow is stable in its composition and flux. The improved vapor deposition method solves the problems encountered with in conventional vapor deposition techniques by providing a vapor deposition method that can be accurately and preferably easily controlled and it does not require the use of a carrier gas. The ionic liquid transfers heat much more efficient in comparison with a solid material or powder. Accordingly, subliming the precursor material from an ionic liquid costs less energy than conventional sublimation processes. After the vaporization process it is possible to regenerate the ionic liquid. Depending on the type and morphology of the impurities, remaining impurities can be separated from the ionic liquid by means of separation technologies and the ionic liquid can then be reused. Moreover, since the ionic liquid is not readily vaporized, the loss of ionic liquid is extremely low. Hence, there is no, or hardly any, consumption of the ionic liquid during the process. Because the precursor material is comprised in the ionic liquid and is vaporized from the ionic liquid, it is relatively easy to control the flux of vaporized precursor material in comparison to conventional techniques. The advantage of using an electrode for supplying the precursor material is that it is easy to handle and its dosimetry can be readily controlled by adjusting the electrical current or voltage of the electrode. The electrode can at the same time be used as a heat source in order to evaporate the cation or salt from the ionic liquid. Furthermore, the method directly provides high purity of the synthesized precursor without the need for separate purification steps.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an apparatus for evaporating a compound comprising a container (1) comprising an ion selective membrane (3) dividing the container in a first compartment (4) for holding an electrolyte (2) and a second compartment (5) for holding an ionic liquid (6) comprising the compound, where the first compartment comprises a cathode (8) and the second compartment comprises an anode (7); a conduit for allowing the ionic liquid comprising the compound to be transported from the second compartment to a film evaporator (10); and a conduit for allowing the ionic liquid to be transported from the film evaporator to the second compartment.    DESCRIPTION OF DRAWING(S) - The figure shows an apparatus for evaporating a compound.    Container (1)    Electrolyte (2)    Ion selective membrane (3)    Anode (7)    Cathode (8)    Film evaporator. (10)