Thin conductive layers of carbon are produced by resistance evaporation of carbon filaments or rods. A high current (approx. 1...5 A) flows through the carbon source, causing it to heat up strongly to a temperature at which carbon evaporates.
Carbon evaporation is usually used for non-conductive samples, for elemental analysis (EDX, WDX) and for the production of thin carbon carrier films for TEM investigations.
ZELMI has carbon evaporation equipment to produce very fine-grained films for high resolution imaging.
The metallic coating is used to make specimens electrically conductive for electron microscopic imaging. Gold and iridium are particularly suitable as noble metals with a high atomic number. However, other metals can also be used, e.g. due to analytical questions, including tungsten, platinum, palladium, silver, copper, nickel, chromium and aluminum or alloys. The decision depends on the sample material and the question.
The coating is carried out in a sputtering process or via thermal evaporation.