Effect of ablated particle flux on MgO nanowire growth by pulsed laser deposition

Oxide nanowire growth using a pulsed laser deposition (PLD) is a promising process since this essentially allows incorporating a rich functionality of various transition metal oxides into nanowires via the heterostructures. Here we investigate the effect of ablated particle flux on magnesium oxide nanowire growth by PLD. When varying the distance between the ablated material and the substrate, the small variation in ablated particle flux generated by a different plume expansion time influences mainly the growth rate while keeping the growth regime. However, varying the laser energy changes not only the growth rate but also the growth regime. Below a critical value of the laser energy the surface morphology tends to show an island growth rather than a nanowire growth. We attribute the existence of such a threshold to the desorption process from the catalyst droplet.