Tungsten-carbon multilayer composition and the effects of annealing: A glancing angle extended x-ray absorption fine structure study

Abstract
Results are presented from a glancing angle extended x‐ray absorption fine structure study to investigate the structure of W/C multilayers and the effects of moderate annealing. There is evidence of considerable interlayer mixing prior to any heat treatment. It is found that after annealing to 350 °C for several hours, drastic changes can occur in the structural environment of the W atoms, with minimal changes in the reflectivity of the sample. There is extensive formation of W2C depending on the W thickness and the W/C ratio. Identification of this carbide as the product of annealing is unambiguous. Above a critical thickness, W begins to grow in its bcc form within the W layer, as it is prepared. This bcc layer is unaffected by the annealing process. The presence of carbon is shown to stabilize the amorphous state of W and inhibits any formation of W2C when the W thickness and W/C ratio are small.