Thermionic Vacuum Arc-A Versatile Technology for Thin Film Deposition and Its Applications

This review summarizes the more-than-25-years of development of the so-called thermionic vacuum arc (TVA). TVA is an anodic arc discharge in vapors of the material to be deposited; the energy for its melting is delivered by means of a focused electron beam. The resulting material ions fall at the substrate where they form a well-adhesive layer; the ion energy is controllable. The deposited layers are, as a rule, free from droplets typical for cathodic arc deposition systems and the thermal stress of the substrates being coated is low. TVA is especially suitable for processing refractory metals, e.g., carbon or tungsten, however, in the course of time, various useful applications of this system originated. They include layers for fusion application, hard coatings, low-friction coatings, biomedical-applicable films, materials for optoelectronics, and for solid-state batteries. Apart from the diagnostic of the film properties, also the diagnostic of the TVA discharge itself as well as of the by TVA generated plasma was performed. The research and application of the TVA proceeds in broad international collaboration. At present, the TVA technology has found its firm place among the different procedures for thin film deposition.