University Siegen, Siegen, Germany
Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
As part of efforts to improve the performance of SRF cavities, the use of alternative structures, such as superconductor-insulator-superconductor (SIS) film coatings have been extensively investigated. Initial efforts using DC magnetron sputtering (MS) deposited NbN films showed the efficacy of this approach. The use of energetic condensation methods, such as high power impulse magnetron sputtering (HiPIMS), have already improved the performance of Nb thin films for SRF cavities and have already been used for nitride film coatings in the tool industry. In this contribution, the results from the deposition of HiPIMS NbN thin films onto oxygen free high conductivity (OFHC) Cu substrates are presented. The effects of the different deposition parameters on the deposited films were elucidated through various characterisation methods, resulting in an optimum coating procedure. This allowed for further comparison between the HiPIMS NbN films and the previously presented DC MS NbN films. The results indicate the improvements offered by HiPIMS deposition, most notably, the significant increase in the entry field, and its applicability to the deposition of SIS films on Cu.
