Smoothening of tungsten-carbon interfaces and change in interface asymmetry on heat treatment

In the present study, interface modifications in tungsten carbon multilayer are analyzed by performing isochronal annealing experiments in the range of 200-800 °C. X-ray reflectivity data revealed that the roughnesses are increasing in the W/C multilayer on going from bottom to top layer. The two interfaces viz W-on-C and C-on-W show an asymmetric change in the roughness values. Transmission electron microscopy results indicate that the interfaces are morphologically smooth but are chemically diffused in nature. Roughnesses are smoothening out after annealing at 400 °C, which results in an increase in the multilayer reflectivity. A possible mechanism of interface smoothening is explained.