Evaporation, sources crucible, electrically

The source can be heated by a variety of techniques. Resistance heating can be used, employing W, Mo, or Ta heater wire or tape. These have the advantage that their low vapour pressures do not cause contamination of the deposit. The source can be contained in a crucible made of boron nitride or titanium diboride. Induction heating can also be used to heat a susceptor source contained in a nonsusceptor crucible. Electric-arc and laser-beam sources can also be used to heat the evaporant. 

Fig. 4. Schematic representation of an electron beam source used for vapour deposition. Electrons are ejected from a hot filament at the back of the crucible housing. The path of the electron beam is controlled by means of electric and magnetic fields. The beam impinges on the metal to be evaporated, contained in. a water-cooled copper crucible. Modulation of the magnetic field is used to increase the effective impingement area of the electron beam.

Radio frequency sources are sources where rf energy is directly inductively coupled into an electrical conductor such as metals or carbon. The rf can be used to heat the source material directly or to heat the container ( susceptor ) that holds the source material. This technique has been particularly useful in evaporating aluminum from BN and BN/TiB2 crucibles. 

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