In-situ monitoring during pulsed laser deposition of layered oxide materials

Abstract

Pulsed Laser Deposition (PLD) has developed from a fast but limited preparation tool towards a competitive thin film deposition technique. One of the advantages above other techniques is the possibility to growth at relative high background pressure, with a large freedom in choosing the kind of gas. In a number of applications, the gaseous species in the background pressure even are part of the elements to be grown. An evidence example is oxygen in the case of high Tc superconductors and giant magnetic resistors. However, the benefit of relative high pressures hampers the use of standard diagnostics and monitor techniques, e.g. Reflective High Energy Electron Diffraction (RHEED), used for thin film growth. With the possibility to use RHEED at standard PLD pressures it became possible to study the growth of oxide materials under different oxygen and temperature conditions. Here, we present the results on applying this technique on SrTiO 3 , which can be grown in different growth modes, depending on temperature and oxygen pressure, during growth. Applying a modified etch technique to SrTiO 3 single crystals, we were able to grow homo-epitaxial SrTiO 3 in a real 2D growth mode. Additional to the usual information obtained with RHEED, another phenomena can be observed. The pulsed way of deposition, characteristic for PLD, leads to relaxations in the intensity of the diffracted pattern. This is caused by the mobility of the deposited material from a disordered distribution till an ordered one. These relaxation times give extra information about relaxation, crystallization, and nucleation of the deposited material. The results obtained from the intensity oscillations as well as relaxations, has led to a different approach to deposit these complex oxide materials, so-called interval deposition. In this contribution first results on this interval deposition will be presented.