Data underlying the publication: Characterization of low-loss hydrogenated amorphous silicon films for superconducting resonators

Superconducting circuit elements used in millimeter-submillimeter (mm-submm) astronomy would greatly benefit from deposited dielectrics with small dielectric loss and noise. This will enable the use of multilayer circuit elements and thereby increase the efficiency of mm-submm filters and allow for a miniaturization of microwave kinetic inductance detectors (MKIDs). Amorphous dielectrics introduce excess loss and noise compared with their crystalline counterparts, due to two-level system defects of unknown microscopic origin. We deposited hydrogenated amorphous silicon films using plasma-enhanced chemical vapor deposition, at substrate temperatures of 100°C, 250°C, and 350°C. The measured void volume fraction, hydro- gen content, microstructure parameter, and bond-angle disorder are negatively correlated with the substrate temperature. All three films have a loss tangent below 10−5 for a resonator energy of 105 photons, at 120 mK and 4 to 7 GHz. This makes these films promising for MKIDs and on-chip mm-submm filters.

在毫米-亚毫米（mm-submm）天文学中使用的超导电路元件，将从具有低介电损耗和低噪声的沉积电介质中极大获益。这将使多层电路元件的使用成为可能，从而提高毫米-亚毫米滤波器的效率，并实现微波动态电感探测器（MKIDs）的小型化。与晶体电介质相比，非晶电介质因来源不明的微观双能级系统缺陷（two-level system defects）而产生额外的损耗和噪声。我们采用等离子体增强化学气相沉积（plasma-enhanced chemical vapor deposition）技术，在100℃、250℃和350℃的衬底温度下沉积了氢化非晶硅薄膜。测得的空隙体积分数、氢含量、微观结构参数和键角无序度均与衬底温度呈负相关。对于谐振器能量为10⁵光子的情况，在120 mK和4至7 GHz条件下，这三种薄膜的损耗角正切均低于10⁻⁵。这使得这些薄膜在MKIDs和片上毫米-亚毫米滤波器的应用中具有良好前景。