Optical, chemical, and depth characterization of Al/SiC periodic multilayers

Abstract

ABSTRACT We present the characterization of Al/SiC periodic multilayers designed for op tical applications. In some samples, a thin layer of W or Mo is added at the SiC-on-Al interfaces. We use x-ray reflectivity (XRR) in order to determine the parameters of the stacks, i.e. thickness and roughness of all the layers. We have performed x-ray emission spectroscopy (XES) to identify the chemical state of th e Al and Si atoms present within the stru cture from an analysis of the shape of the Al KE and Si KE emission bands. Finally, time of flight secondary ion mass spectrometry (ToF-SIMS) is used to obtain the depth profile of the different elements present within the studied stacks. A fit of the XRR curves shows that the Al/SiC multilayer present large interfacial roughness (up to 2.8 nm), which is decreased considerably (down to 1 nm or less) when the refractory metal layers are introduced in the periodic structure. The combination of XES and ToF-SIMS allows us to conclude that in these systems the roughness is a purely geometrical parameter and not related to chemical interfacial reactions. Keywords: periodic multilayer, x-ray emission, x-ray reflectivity, time of flight secondary ion mass spectrometry * philippe.jonnard@upmc.fr , phone 33 1 44 27 63 03, fax 33 1 44 27 62 26, www.lcpmr.upmc.fr/