Characteristic of the carbon–tungsten co-deposition layers prepared by RF magnetron sputtering in a D2/Ar plasma

Abstract

A C–W co-deposition layer, formed by radio frequency magnetron sputtering, was investigated to identify the characteristics of C–W mixed layers in fusion experimental reactors. The layers were characterized by ion beam analysis, Raman spectroscopy, X-ray diffraction and scanning electron microscopy. It was found that D atoms in C–W layers were mainly trapped by the C atoms. The ratio of C/W and D concentrations in the C–W layers deposited at a pressure of 5.0Pa and a fixed flow rate ratio were 54/31 and 5%, respectively. They all increased significantly with increased flow rate of D2 but decreased with temperature at a relatively low level. The pressure dependence of the D concentration showed a maximum value around 5Pa and it decreased with rising or decreasing pressure. Both Raman and X-ray analysis revealed that the structure of the C–W layers became more graphite-like with increasing temperature. Moreover, deuterium introduction made the tungsten carbide phase disappear in the deuterated C–W layers. Only erosion caves on the surface of the sample prepared at 300K were observed by SEM. When the temperature increased, they disappeared, and convex bodies appeared.