Application of ultrafast pulsed-laser deposition system for plasma-enhanced thin-film growth of III-nitrides

Summary form only given. Ultrafast laser plasmas have unique features compared to conventional (nanosecond) plasmas. Their time evolution is separated from the laser pulse allowing for pre-tuning of the plasma through variation of the pulse parameters. High ionic charge states exist in the expanding plasma which allow for multiple reaction channels in the background gas dynamics. Fast electrons provide a high-energy ion component beyond hydrodynamics which admits additional energy into both the film for ion-assisted growth and the background gas for reactive-gas growth. For higher-intensity laser pulses, the fast electrons can ionize the background gas, providing a plasma-enhanced thin-film growth. For intensities closer to the ablation threshold, a high-voltage grid can be used to accelerate the free electrons from the ablation plasma and ionize the background gas. The combination of a tunable ultrafast laser and a versatile deposition system allows broad-based control of the ablation plasma and the thin-film growth process. Such an ultrafast pulsed-laser deposition (PLD) system has been built for the plasma-enhanced thin-film growth of III-nitrides.