Using an external electric field to reduce laser damage of DLC films

Unbalanced magnetron sputtering (UBMS) was used to deposit a diamond-like carbon (DLC) film on Si substrates. The film was subjected to a laser to result damages both before and after an external electric field was applied. A contrast of the damages shows that the external electric field improves the film’s laser induced damage threshold (LIDT) from 0.70 J/cm2 up to 0.82 J/cm2; when the optical energy is maintained at 1.88 J/cm2, the damaged area of the film decreases with increasing external electric field. The results show that the external electric field influences the anti-laser-damage ability of a DLC film because both the photoelectrons produced by the excitation from the laser and the free electrons in the DLC film can move quickly within the film. This movement indirectly decreases the energy density in the laser-irradiated area and slows down the DLC film’s graphitisation process, consequently improving the film’s ability to withstand laser damage.