High Q-Factor Millimeter-Wave Silicon Resonators

Resonators made of high-resistivity silicon (HRS) have been manufactured, and their characteristics were measured at a frequency range from 20 to 50 GHz. To study the influence of the material resistivity on Q-factor values, two HRSs were used. The first one was as-grown high-purity floating zone (FZ) silicon with a resistivity of $\sim 70~\text{k}\Omega ~\cdot $ cm. The second was FZ silicon irradiated with high-energy protons. The resistivity of the irradiated silicon was essentially the same as that of intrinsic silicon with a resistivity of $\sim 400~\text{k}\Omega ~\cdot $ cm at room temperature. Several whispering gallery modes were identified and measured on disk shape samples made on both materials. At room temperature and at a frequency of 50 GHz, the Q-factor values for the resonators made of the as-grown and the irradiated silicon are up to $1.8 \times 10^{4}$ and up to $6 \times 10^{4}$ , respectively.