Low two-level-system noise in hydrogenated amorphous silicon

TL;DR

This study demonstrates significantly reduced two-level-system noise in hydrogenated amorphous silicon films at sub-Kelvin temperatures, enhancing the performance of superconductive resonator devices.

Contribution

It reports the first measurement of TLS noise in PECVD-deposited a-Si:H films, achieving noise levels over five times lower than previous amorphous dielectrics.

Findings

TLS noise in a-Si:H is substantially lower than in other amorphous dielectrics.

The results are comparable to crystalline dielectric resonators.

Improved fabrication recipes lead to enhanced device performance.

Abstract

At sub-Kelvin temperatures, two-level systems (TLS) present in amorphous dielectrics source a permittivity noise, degrading the performance of a wide range of devices using superconductive resonators such as qubits or kinetic inductance detectors. We report here on measurements of TLS noise in hydrogenated amorphous silicon (a-Si:H) films deposited by plasma-enhanced chemical vapor deposition (PECVD) in superconductive lumped-element resonators using parallel-plate capacitors (PPCs). The TLS noise results presented in this article for two recipes of a-Si:H improve on the best achieved in the literature by a factor >5 for a-Si:H and other amorphous dielectrics and are comparable to those observed for resonators deposited on crystalline dielectrics.