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Diamond serves as an attractive material for microelectromechanical systems (MEMS) owing to its superior properties, including high mechanical strength, low coefficient of thermal expansion and the highest thermal conductivity among semiconductors. To achieve reliable mechanical design and performance prediction of diamond-based MEMS devices, accurate knowledge of its elastic properties, especially Young’s modulus, is crucial. However, the reported value for the Young’s modulus of practical single-crystal diamond (SCD) varies greatly due to its elastic anisotropy, which has yet to be extensively investigated.
[Experiment] To understand the Young’s modulus anisotropy of SCD, we designed a “wagon-wheel” structure comprising circle-array SCD microcantilevers on a (001) diamond substrate, where the cantilever orientations span from 0° to 360° in 15° increments. The out-of-plane resonance frequencies of the SCD cantilevers, actuated by a piezoelectric ceramic, were measured in a vacuum (10−5 Torr) with a laser Doppler vibrometer. By applying the Euler–Bernoulli beam equation as shown below, the Young’s modulus of cantilevers oriented in different directions can be derived.
[Result] Figure 1(a) illustrates the SCD cantilevers with a ‘wagon-wheel’ structure on the (001) crystal plane. All cantilevers have an identical length of 100~120 μm, a thickness of approximately 1~2 μm and a width of 12 μm. A representative set of 1st order resonance spectra from cantilevers are presented in Fig. 1(b)-(d). By calculating the Young’s modulus along various directions in the (001) plane of diamond, we found that SCD cantilevers oriented along the <100> and <110> directions exhibit the minimum and maximum modulus values, respectively, which agrees well with the theoretical rotational dependence of Young’s modulus.

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Keyword: Diamond, MEMS

Conference: 2025年第86回応用物理学会秋季学術講演会 (2025-09-07 - 2025-09-10)

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Manuscript type: Not a journal article

MDR DOI: https://doi.org/10.48505/nims.5857

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Updated at: 2025-11-06 12:30:27 +0900

Published on MDR: 2025-11-06 12:24:57 +0900