Ultrananocrystalline diamond prepared by pulsed laser deposition

Ultrananocrystalline diamond (UNCD) and sp2 amorphous carbon composite thin films were grown on sapphire (0001) substrates heated to 550 °C in 4 Torr hydrogen by pulsed laser deposition (PLD) using a graphite target. Transmission electron microscopy revealed that the deposited films consisted of dense non-oriented UNCDs with diameters of approximately 5 nm. The central area of the film, corresponding to the plume center, shows the maximum film thickness and maximum density of UNCDs. In order to achieve UNCD growth by PLD, it is critical that highly energetic species arrive in high density at the substrate accompanied by sufficient ambient hydrogen.