The thermal expansion mismatch of thermal grown silica on a silicon wafer is well known to induce compressive stress upon cooling from the growth temperature to room temperature. In this Letter, we investigate how this stress impacts silica disk structures by comparison of measurements with both a finite element and an analytical model. The disk structures studied are also whispering gallery optical resonators, and proper control of stress is critical to obtain high-Q resonances. Based on our analysis, thicker oxide layers and proper control of undercut enable ultra-high-Q optical performance and mechanical stability.
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Research Article| January 24 2013
Thermal stress in silica-on-silicon disk resonators
Tong Chen, Hansuek Lee, Kerry J. Vahala; Thermal stress in silica-on-silicon disk resonators. Appl. Phys. Lett. 21 January 2013; 102 (3): 031113. https://doi.org/10.1063/1.4789370
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