In-Situ monitoring of laser ablation of superconductors

Abstract

In general, the preparation of superconductive thin film involves the vaporization of various chemicals. The species deposited on substrates include neutral atoms or molecules in ground states, atoms and molecules in excited states, ions in ground states and ions in excited states. An instrument which has the capability of the quantitative determination of atoms, molecules, and ions in various electronic states should provide very detailed information on the mechanism of formation of superconductive films. A position sensitive monitor of various oxide compounds relative to the flow and pressure of oxygen should reveal the role of oxygen, in superconductive film preparation. An ideal method of monitoring the deposition process is to continuously track the deposition in situ and automatically maintain optimum film growth. With this goal in mind, we have investigated several diagnostic methods. In this work, fluorescence spectra are presented which indicate suitability for monitoring excited atoms, molecules and ions; mass analysis of laser desorbed ions is described; and the application of resonance ionization spectroscopy (RIS) to monitor desorbed neutral atoms and molecules is discussed. FTIR spectroscopy is used to measure substrate temperatures and the components on the surfaces. 23 refs., 1 tab.