Butz, Benjamin
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Publication Access status: Metadata only , HiPIMS deposition of superconducting Nb thin films onto Cu substrates(2023); ; ; ; The use of energetic condensation techniques, such as HiPIMS, has the potential to significantly improve the superconducting performance of coated Cu cavities by producing bulk-like Nb thin films. However, in order to benefit from these techniques, a deeper understanding of the effects of, and the relationship between, the different deposition parameters, the physical properties of the deposited films and the superconducting performance of the films, is still required. This contribution details the effects of different HiPIMS deposition parameters on the morphological, crystallographic and superconducting properties of Nb thin films deposited onto electropolished Cu substrates. Higher duty cycles (8 – 20 %) than previous HiPIMS investigations were used in the majority of the coatings. The films displayed more bulk-like crystallographic properties, indicated here by the lattice parameter, with a “transition zone” apparent in the early stages of film growth. A reduction in the surface roughness as well as interfacial voids, compared to typical DC MS Nb films, was also observed. The superconducting performance of the films, specifically the first magnetic flux entry field, showed a marked reliance on the substrate bias and the film thickness. Conversely, the HiPIMS duty cycle appears to have a comparatively insignificant effect. •Investigation of multiple HiPIMS coating parameters for the deposition of Nb thin films onto Cu substrates.•Predicted improved interface and surface roughness observed across all HiPIMS samples.•A morphological/crystallographic “transition zone” is observed between 1 and 2 μm film thickness.•Superconducting performance of Nb films directly linked to their crystallographic properties, i.e. lattice parameter and crystallite size.•HiPIMS duty cycle does not appear to influence the superconducting performance of Nb thin films.Source Type:Article2 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Single-photon emission from silicon-vacancy color centers in polycrystalline diamond membranesSingle-color centers in thin polycrystalline diamond membranes allow the platform to be used in integrated quantum photonics, hybrid quantum systems, and other complex functional materials. While single-crystal diamond membranes are still technologically challenging to fabricate as they cannot be grown on a non-diamond substrate, free-standing polycrystalline diamond membranes can be conveniently fabricated at large-scale from nanocrystalline diamond seeds on a substrate that can be selectively etched. However, their practical application for quantum photonics is so far limited by crystallographic defects, impurities, graphitic grain boundaries, small grain sizes, scattering loss, and strain. In this paper, we report on a single-photon source based on silicon-vacancy color centers in a polycrystalline diamond membrane. We discuss the spectroscopic approach and quantify the photon statistics, obtaining a g2(0) ≈ 0.04. Our findings hold promise for introducing polycrystalline diamond to quantum photonics and hybrid quantum systems.Source Type:Article2
