Formation of Droplets on Thin Film Surface in Pulsed Laser Deposition Using Metal Targets
MUSTOFA Salim, Satoshi TSUYUGUCHI, Takao ARAKI, Minoru NISHIDA, Takanori HINO
The relationship between the morphology of Au, Cu and Ag metal targets and the formation of droplets on the metal thin films was investigated using the Pulsed Laser Deposition (PLD). The metal thin films were made from the metal targets by irradiating KrF excimer laser at various laser fluences from 2. 5 J/cm2 to 10 J/cm2 in a vacuum chamber. The surface morphology of the target after laser irradiation was observed by a Scanning Electron Microscope (SEM). It was found that spouting holes occurred on the surface of the Cu target after laser irradiation at the laser fluence of 10 J/cm2. Droplets of about 1 (m in diameter were found around the spouting holes. Oxygen, Phosphor and Sulphur were detected at the spouting holes from Energy Dispersive X-Ray (EDX) analyses. However, at the laser fluence of 2. 5 J/cm2 spouting holes were not found. The observation on the surface of metal thin film indicates that particles of about 1 μm in diameter fly out away from the target and then reach on the surface of substrate with high velocity as droplets. The same phenomenon was observed when Ag and Au targets were used. In the case where a high purity of Cu (111) single crystal target was used, it was obvious that the surface morphology of the target after laser irradiation would be good enough at the central zone subjected to the laser irradiation of higher laser energy than at the circumference zone.