| AVS 66th International Symposium & Exhibition | |
| Thin Films Division | Monday Sessions |
| Session TF+SE-MoA |
| Session: | HiPIMS and Reactive HiPIMS for Novel Thin Films |
| Presenter: | Trent Borman, The Pennsylvania State University |
| Authors: | T. Borman, The Pennsylvania State University M.D. Hossain, The Pennsylvania State University J.-P. Maria, The Pennsylvania State University |
| Correspondent: | Click to Email |
Sputtered carbide thin films frequently feature significant carbon sub-stoichiometry irrespective of the source materials, while amorphous-C or a-C:H secondary phases begin to precipitate with as many as 1/3 or more of the carbon sites vacant in the rock salt structure. In reactive sputtering it is often necessary to sputter in the compound regime in order to achieve a higher carbon stoichiometry, however this comes with the penalty of reduced sputter yield. Reactive HiPIMS can avoid carburization of the target through gas rarefaction and high target etch rates. While this is beneficial for process stability, carbide microstructural evolution is still limited by the low homologous temperature achievable in thin film deposition (0.25-0.3Tmelt). Recently, bipolar-HiPIMS has been discussed as a means of tailoring the bombardment in order to drive microstructural development through momentum transfer and thermalization of kinetic energy.
The authors will discuss the reactive synthesis of high entropy carbide films from metal alloy targets using Bipolar High-Power Impulse Magnetron Sputtering (B-HiPIMS) in a mixed Ar/CH4 atmosphere. The effects of bipolar pulse voltages and lengths on microstructural, compositional, and phase development will be discussed. Additionally, the impacts of order of magnitude changes in sputter pulse length on the formation of carbide thin films will be reported. This work investigates a broad range of carbon stoichiometries: from metallic films and carbon deficient carbides to near stoichiometric carbides and carbide/amorphous-carbon nanocomposites. This enables investigation of the property trends as a function of carbon content, as it is presently unclear if the diverse trends observed in the binary carbides persist in a high entropy system or are overshadowed by the high entropy metal sublattice.
This material is based upon work supported by the National Science Foundation Graduate Research Fellowship (DGE-1252376) and the Office of Naval Research (N00014-15- 1-2863).