Thermal stability of 2.4 nm period Ni-Nb/C multilayer x-ray mirror

Abstract

The structure of Ni-Nb/C multilayers as a function of annealing at 200 and 320°C has been studied. The layered structure is found to be extremely stable even after annealing at 320°C. The interdiffused layer present at the two interfaces Ni1/2Nb1/2/C and C/Ni1/2Nb1/2 before annealing undergoes a reverse diffusion on annealing leading to an increase in repeat unit thickness as well as reflectivity enhancement. The repeat unit thickness increases from 2.36 to 2.56 nm and the reflectivity at the first order peak increases by 5 times after annealing at 320°C. Only the Ni1/2Nb1/2 layers in the multilayer undergo a crystalline transformation into an equilibrium NiNb compound without increasing the interface roughness. © 2000 American Institute of Physics.