Organic material deposition requires uniform and precise heating with excellent temperature and deposition rate control. This is commonly achieved using a source similar to an effusion furnace (also known as a knudsen cell or k-cell). In this type of source, evaporation of the target material occurs via electrical (Joule) heating of a refractory metal filament coiled around a metal, ceramic, or quartz crucible. The crucible is heated above the melting or sublimation point of the source material to create adequate vapor pressure for deposition.

This style of source is very well suited for depositing organic materials, although the right choice of crucibles allows metal deposition as well. Effusion sources have an integrated thermocouple for temperature feedback. The temperature control allows for process flexibility and enables the heating of organic materials to its ideal sweet-spot: the temperature just above what is required to create adequate vapor pressure but below its decomposition temperature. In addition, using the temperature PID control, the sources can be heated to just above the boiling temperature of water to remove moisture from the organic materials which can be one of the major sources of organic film degradation.