One of the critical elements in the manufacture of long lengths of high temperature superconducting wires is the development of deposition diagnostics correlated with the quality of deposited material for process control. Fast imagery, emission spectroscopy, and time-of-flight spectroscopy of the very energetic plumes resulting from the pulsed laser deposition of YBa2Cu3O7-x have been recorded for a wide range of deposition conditions at four military, DoE, and industrial facilities. Several optical signatures that are strongly correlated with the deposited critical currents have been identified with strong potential for process control. In addition, the partioning of energy among translation, electronic and ro-vibrational degrees of freedom as a function of laser fluence, chamber pressure, and position in the plume have been characterized.
High quality thin films (100nm to several 1000nm) of many complex material systems such as the high temperature superconductor YBCO, have been deposited using pulsed laser ablation. Long lengths of high quality YBCO on metallic conductors are needed to meet industrial and government requirements. Although, pulsed laser deposition (PLD) grows the best YBCO films on meter lengths of metallic conductors, it has not been proven to be a consistent manufacturing process. PLD is simple in concept but has quite complicated plume and growth dynamics which are not well understood. In this study we use in-situ time-resolved mesurements of collision-driven plume emissions to characterize critical deposition parameters and to develop a computational model which includes these dynamics in a reacting PLD plume.
Rand Biggers, Paul Murray, David Mast, I. Maartense, T. Peterson, D. Dempsey, C. Varanasi, S. Murray, D. Lubbers, S. Laube, B. Lovett, Eric Moser, J. Brown, D. Liptak, John Busbee
We examine the time-resolved spectral components emitted at approximately 327 nm and approximately 550 nm in YBCO plumes during pulsed laser deposition of thin films using a KrF excimer laser at (lambda) equals 248 nm. The studied emission signals last for approximately 20 microsecond(s) ec, and show variations when process parameters such as laser power, laser excitation voltage, beam focus, chamber pressure, substrate temperature, pulse repetition rate, and target rotation rate are changed. These signals are also dependent on other factors such as target wear and age of the laser gas mixture. Spectral-component monitoring is a supplementary method of real-time plume evaluation, and allows observation of changes both prior to deposition and during the actual deposition. Adjustments can be made to the process parameters to make the plume conform to criteria necessary for the growth of films with specific qualities. The use of these spectral components as real-time process- control state variables for more reproducible fabrication of high quality thin films will be assessed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.