| We present the results of optical and ion probe diagnostics of pulsed laser-deposition. The dynamics of laser-ablated plumes and the effect of ambient pressure, laser spot-size, laser fluence and in-situ ring electrode have been investigated in detail, in time-resolved as well as time-integrated modes. Ion probes were used to study the ionic content of the plume. The role of ions in improving the quality of the films has been investigated. Plots employing the Line Intensity Ratio method were used to estimate plasma temperature and atomic density at different spatial locations in the plume. Non-emissive species in the plume were probed by using Laser Induced Fluorescence. Details of a novel dual-laser ablation scheme for the reduction of particulate density and the expansion of the plume for large-area deposition are presented as a significant improvement over any previous attempt to resolve the problems intrinsic to pulsed laser deposition. The dynamics of dual-laser ablation have been explored through surface-reflectivity measurements at the target and plume expansion measurements, and an attempt has been made to correlate plume expansion to large-area deposition via ex-situ thickness profile measurements. Both ion probe measurements and optical emission spectroscopy reveal the advantages of the dual laser ablation technique. |
