Geometry dependence of TLS noise and loss in a-SiC:H parallel plate capacitors for superconducting microwave resonators

Abstract

Parallel plate capacitors (PPC) significantly reduce the size of superconducting microwave resonators, reducing the pixel pitch for arrays of single photon energy-resolving kinetic inductance detectors (KIDs). The frequency noise of KIDs is typically limited by tunneling Two-Level Systems (TLS), which originate from lattice defects in the dielectric materials required for PPCs. How the frequency noise level depends on the PPC's dimensions has not been experimentally addressed. We measure the frequency noise of 56 resonators with a-SiC:H PPCs, which cover a factor 44 in PPC area and a factor 4 in dielectric thickness. To support the noise analysis, we measure the TLS-induced, power-dependent, intrinsic loss and temperature-dependent resonance frequency shift of the resonators. From the TLS models, we expect a geometry-independent microwave loss and resonance frequency shift, set by the TLS properties of the dielectric. However, we observe a thickness-dependent microwave loss and resonance frequency shift, explained by surface layers that limit the performance of PPC-based resonators. For a uniform dielectric, the frequency noise level should scale directly inversely with the PPC area and thickness. We observe that an increase in PPC size reduces the frequency noise, but the exact scaling is, in some cases, weaker than expected. Finally, we derive an engineering guideline for the design of KIDs based on PPC-based resonators.

13 pages, 11 figures

References in corpus (13)

• Experimental evidence for a surface distribution of two-level systems in superconducting lithographed microwave resonators
• Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures
• A semi-empirical model for two-level system noise in superconducting microresonators
• Generalized Tunneling Model for TLS in amorphous materials and its predictions for their dephasing and the noise in superconducting microresonators
• Contribution of dielectrics to frequency and noise of NbTiN superconducting resonators
• Single crystal silicon capacitors with low microwave loss in the single photon regime
• Superconducting NbTiN Thin Films with Highly Uniform Properties over a 100 mm diameter Wafer
• Reduced frequency noise in superconducting resonators
• Ultra-sensitive Super-THz Microwave Kinetic Inductance Detectors for future space telescopes
• Reactive magnetron sputter deposition of superconducting niobium titanium nitride thin films with different target sizes
• Hydrogenated Amorphous Silicon Carbide: A Low-loss Deposited Dielectric for Microwave to Submillimeter Wave Superconducting Circuits
• Resolving Power of Visible to Near-Infrared Hybrid $\beta$-Ta/NbTiN Kinetic Inductance Detectors
• Compact superconducting microwave resonators based on Al-AlOx-Al capacitor