Growth of ZnO nanoparticles and nanorods with ultrafast pulsed laser deposition

In this work, we study the application of ultrafast pulsed laser deposition (PLD) in ZnO nanomaterial synthesis, including nanoparticles and nanorods. PLD using long pulse (nanosecond) lasers has been widely used as a method for growing prototype materials. The recently-emerged ultrafast PLD is expected to be able to overcome the problem of large liquid droplet formation. Using near infrared and femtosecond laser pulses in ablation, we first characterize the ablation plume using a Langmuir probe and plasma optical emission spectroscopy. We then examine the structural properties of the nanoparticles generated during low-fluence ablation. Finally, we demonstrate that using nanoparticle aggregates as templates, assisted by plume-excited nitrogen radicals at a high fluence, high quality ZnO nanorods can be grown free of metal catalysts.