Effects of Process Parameters on the Microstructural Characteristics of DC Magnetron Sputtered Molybdenum Films on Graphite Substrate

摘要

Graphite, due to its extreme purity and high-temperature stability, is considered as the material of choice for nuclear fusionreactors. However, it undergoes rapid oxidation and erosion at extreme environmental conditions like those experienced bythe plasma-facing components (PFCs) of a fusion reactor. On the other hand, molybdenum (Mo) does offer a combination ofthermal, mechanical, and chemical properties that make it an aspirant candidate for PFCs and other applications demandingsubstantial physical, chemical, and thermal stability as well as significant thermal conductivity. Mo films on graphite isone of the attractive options to sustain against such harsh environmental conditions. Here, in this work, we develop Mofilms over graphite substrate through sputter deposition and analyze the effects of process parameters like the sputter powerand the substrate temperature on the morphology and film quality. It is shown that an increase in sputter power, as well assubstrate temperature, induces significant changes in the topography of the films. For low-temperature depositions, the grainmorphology does not change with increasing sputter power, however, for relatively higher substrate temperatures, significantchanges in morphology are observed with increasing sputter power. Similarly, dependences of crystallite size, film roughness,and electrical conductivity are discussed with changing sputter power and substrate temperature. Our results suggest that thekinetic energy of the sputteredMo particles plays a crucial role in determining the final film quality. This study manifests thatoptimum sputter parameters guarantee quality Mo films over graphite substrate.