Data underlying the publication: Vibrational modes as the origin of dielectric loss at 0.27–100 THz in a-SiC:H

Low-loss deposited dielectrics are beneficial for the advancement of superconducting integrated circuits for astronomy. In the microwave band (∼1–10 GHz) the cryogenic and low-power dielectric loss at cryogenic temperatures and low electric field strengths is dominated by two-level systems. However, the origin of the loss in the millimeter-submillimeter band (∼0.1–1 THz) is not understood. We measured the loss of hydrogenated amorphous SiC (a-SiC:H) films in the 0.27–100 THz range using superconducting microstrip resonators and Fourier-transform spectroscopy. The agreement between the loss data and a Maxwell-Helmholtz-Drude dispersion model suggests that vibrational modes above 10 THz dominate the loss in the a-SiC:H above 200 GHz.

低损耗沉积电介质对于面向天文领域的超导集成电路的发展具有重要意义。在微波波段（约1~10 GHz）内，低温、低电场强度条件下的低功耗介电损耗主要由二能级系统（two-level systems）主导。然而，毫米-亚毫米波段（约0.1~1 THz）内该损耗的起源仍未明确。本研究采用超导微带谐振器与傅里叶变换光谱法，测试了氢化非晶碳化硅（hydrogenated amorphous SiC, a-SiC:H）薄膜在0.27~100 THz频段内的损耗特性。损耗数据与麦克斯韦-亥姆霍兹-德鲁德色散模型的吻合度良好，表明在200 GHz以上的频段中，10 THz以上的振动模式主导了a-SiC:H的介电损耗。