Proton radiation effects on optically transduced silicon carbide microdisk resonators

Abstract

Circular microdisk mechanical resonators vibrating in their various resonance modes have emerged as important platforms for a wide spectrum of technologies including photonics, cavity optomechanics, optical metrology, and quantum optics. Optically transduced microdisk resonators made of advanced materials such as silicon carbide (SiC), diamond, and other wide- or ultrawide-bandgap materials are especially attractive. They are also of strong interest in the exploration of transducers or detectors for harsh environments and mission-oriented applications. Here we report on the first experimental investigation and analysis of energetic proton radiation effects on microdisk resonators made of 3C-SiC thin film grown on silicon substrate. We fabricate and study microdisks with diameters of ∼48 µm and ∼36 µm, and with multimode resonances in the ∼1 to 20 MHz range. We observe consistent downshifts of multimode resonance frequencies, and measure fractional frequency downshifts from the first three flexural resonance modes, up to ∼-3420 and -1660 ppm for two devices, respectively, in response to 1.8 MeV proton radiation at a dosage of 1014/cm2. Such frequency changes are attributed to the radiation-induced Young’s modulus change of ∼0.38% and ∼0.09%, respectively. These devices also exhibit proton detection responsivity of ℜ ≈ -5 to -6 × 10−6 Hz/proton. The results provide new knowledge of proton radiation effects in SiC materials, and may lead to better understanding and exploitation of micro/nanoscale devices for harsh-environment sensing, optomechanics, and integrated photonics applications.