Physical vapour deposition of NbTiN thin films for superconducting RF cavities.

The production of superconducting coatings for radio frequency (RF) cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. The use of thin films made from superconductors with thermodynamic critical field, Hc > HC(Nb), allows the possibility of multilayer superconductor – insulator – superconductor (SIS) films and accelerators that could operate at temperatures above 2 K. SIS films theoretically allow increased acceleration gradient due to magnetic shielding of underlying superconducting layers [1] and higher operating temperature can reduce cost [2]. High impulse magnetron sputtering (HiPIMS) and pulsed DC magnetron sputtering processes were used to deposit NbTiN thin films onto Si(100) substrate. The films were characterised using scanning electron microscopy (SEM), x-ray diffraction (XRD), Rutherford back-scattering spectroscopy (RBS) and a four-point probe

Physical vapour deposition of thin films for use in superconducting RF cavities

The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction and DC SQUID magnetometry

Development of thin films for superconducting RF cavities

Superconducting coatings for superconducting radio frequency (SRF) cavities is an intensively developing field that should ultimately lead to acceleration gradients better than those obtained by bulk Nb RF cavities. ASTeC has built and developed experimental systems for superconducting thin-film deposition, surface analysis and measurement of Residual Resistivity Ratio (RRR). Nb thin-films were deposited by magnetron sputtering in DC or pulsed DC mode (100 to 350 kHz with 50% duty cycle) with powers ranging from 100 to 600 W at various temperatures ranging from room temperature to 800 °C on Si (100) substrates. The first results gave RRR in the range from 2 to 22 with a critical temperature Tc ≈ 9.5 K. Scanning electron microscopy (SEM), x-ray diffraction (XRD), electron back scattering diffraction (EBSD) and DC SQUID magnetometry revealed significant correlations between the film structure, morphology and superconducting properties

High power impulse magnetron sputtering of thin films for superconducting RF cavities

The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. The use of thin films made from superconductors with thermodynamic critical field, Hc>Hn/cb, allows the possibility of multilayer superconductor – insulator – superconductor (SIS) films and also accelerators that could operate at temperatures above the 2 K typically used. SIS films theoretically allow increased acceleration gradient due to magnetic shielding of underlying superconducting layers [1] and higher operating temperature can reduce cost [2]. High impulse magnetron sputtering (HiPIMS) and pulsed DC magnetron sputtering processes were used to deposit NbN and NbTiN thin films onto Si(100) substrate. The films were characterised using scanning electron microscopy (SEM), x-ray diffraction (XRD), Rutherford back-scattering spectroscopy (RBS) and a four point probe