TEM and Raman scattering investigation of carbon in annealed Co/C soft X-ray multilayers

Abstract

The structures of the carbon sublayers in the annealed Co/C soft X-ray multilayers fabricated by using a dual-facing-target sputtering system have been characterized by transmission electron microscopy (TEM) and Raman spectroscopy (RS). The results suggest that the structural variations in the carbon layers can be roughly divided into three stages, i.e. ordering, crystalline and grain growth stages. At the ordering stage with annealing temperatures below 400°C, the amorphous carbon layers change from ones of bond-angle disorder and fourfold-bonding only to ones of threefold-bonding. At the crystalline stage, the amorphous carbon layers in the as-deposited multilayers crystallize to graphite crystallites in the annealing temperature range of 500–600°C. At the grain growth stage, the specimens are annealed at temperatures higher than 700°C. A growth in the graphite crystallite dimensions is observed, which is consistent with the TEM results.