Structure and stability of laser deposited ZrO2/Ti and ZrO2/MgO multilayers

ZrO2/Ti and ZrO2/MgO thin multilayer systems have important applications in X-ray optics, especially in the 'water window' regime (wavelength: 2.3-4.4 nm) as X-ray mirrors and multilayer Laue lenses. For this purpose the knowledge of the thermal stability of these multilayer systems is necessary. Thus, in this contribution the structure and stability of ZrO2/Ti and ZrO2/MgO multilayers is presented. The films were prepared on Si substrates using pulsed laser deposition (PLD) in ultra high vacuum. During heating the phase transformations of the components were studied using in-situ X-ray reflectometry (XRR) and in-situ X-ray diffraction (XRD). Furthermore, the changes in the structure were observed by in-situ transmission electron microscopy (TEM). The observed results are discussed with respect to the processes occuring during annealing of the multilayers (structural changes, crystallization of the amorphous oxides, changes in the oxygen content of the layers..).