Abstract

Little is known about the physics of film growth with laser evaporation, compared with more conventional techniques such as thermal or sputtering. For example, there is evidence that the atomic nature of the laser evaporated materials may be responsible for the observed epitaxial growth at comparatively low temperatures. It is of fundamental interest to study the physical processes which lead to such results. Oxides (ZnO, Al₂O₃, SiO₂) and fluorides (PbF₂), which have been used to form high quality optical thin films, were evaporaed using a CO₂ TEA laser with power densities exceeding 10⁹W/cm². The chemical state (atoms, molecules, or clusters) of the evaporants was determined using a residual gas analyzer (RGA). The relative concentrations of the different chemical species were measured as a function of laser conditions. Using the RGA in conjunction with a time-of-flight apparatus, the kinetic energy of the evaporants was also studied as a function of laser conditions. Finally, the effect of reactive (O₂) and inert (N₂, He) gases on the evaporation process was also studied.

© 1985 Optical Society of America