The goal of this research project is to provide an improved mapping of the dynamics and the chemistry taking place in the plasma plumes that are being used in pulsed laser deposition (PLD) for thin film growth. Especially the influence of external PLD parameters, such as ablation laser fluence and background gas composition and pressure, on the plasma dynamics and chemistry are of interest to us, as we believe this is the key to an improved understanding and control of stoichiometric film growth.
We employ a combination of laser induced fluorescence (LIF) and absorption spectroscopy (AS). This allows for in-situ spatiotemporal
mapping of the absolute densities of plasma constituents. A dye laser combined with second harmonic generation provides an
extremely wide range of wavelengths that can be produced (250 — 900 nm) and thus a wide range of materials that can be detected. It also enables high chemical selectivity, due to a very narrow linewidth, ensuring only a single plasma constituent will be detected at any one time. Spatial resolution is provided by shaping the LIF excitation beams with special optics, allowing for mapping of thin cross-sections of the plasma plume. The short pulse length of the dye laser (7 ns FWHM), in combination with a high-speed camera, provide the temporal resolution.