Pulsed laser deposition of thin films is a technology whose fundamental processes are often poorly understood. Because of the difficulty of monitoring in real time either the ablation process itself (the laser-solid interaction), or thin film growth (plume-substrate interaction), studies have largely relied on diagnostic studies of the ablated plume and the resulting film to infer details about other steps in the process. Information gained from this approach has helped improve the production of high-temperature superconducting thin films.
We have studied plume dynamics during the in-situ pulsed laser deposition of YBa2Cu3O7−δ thin films. The 248 and 308 nm lines of an excimer laser were used to generate a plume from a bulk YBa2Cu3O7−δ target. Both fast intensified CCD imaging and spectral diagnostics were used to monitor plume dynamics. Variations in the plume distribution as a function of processing gas, pressure, fluence, energy, and spot size were monitored by film composition and spectral-and time-resolved imaging.