Abstract Nanocrystalline materials exhibit properties that can differ substantially from those of their single crystal counterparts. As such, they provide ways to enhance and optimize their functionality for devices and applications. Here, we report on the optical, mechanical and thermal properties of nanocrystalline silicon probed by means of optomechanical nanobeams to extract information of the dynamics of optical absorption, mechanical losses, heat generation and dissipation. The optomechanical nanobeams are fabricated using nanocrystalline films prepared by annealing amorphous silicon layers at different temperatures. The resulting crystallite sizes and the stress in the films can be controlled by the annealing temperature and time and, consequently, the properties of the films can be tuned relatively freely, as demonstrated here by means of electron microscopy and Raman scattering. We show that the nanocrystallite size and the volume fraction of the grain boundaries play a key role in the dissipation rates through nonlinear optical and thermal processes. Promising optical (13,000) and mechanical (1700) quality factors were found in the optomechanical cavity realized in the nanocrystalline Si resulting from annealing at 950°C. The enhanced absorption and recombination rates via the intragap states and the reduced thermal conductivity boost the potential to exploit these nonlinear effects in applications including Nanoelectromechanical systems (NEMS), phonon lasing and chaos-based devices.

中文翻译：

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光机械探测纳米晶硅的性质

摘要 纳米晶材料表现出的特性可能与其单晶对应物的特性大不相同。因此，它们提供了增强和优化设备和应用程序功能的方法。在这里，我们报告了通过光机械纳米束探测的纳米晶硅的光学、机械和热特性，以提取光吸收、机械损耗、热量产生和耗散的动力学信息。使用通过在不同温度下对非晶硅层进行退火制备的纳米晶薄膜来制造光机械纳米束。由此产生的微晶尺寸和薄膜中的应力可以通过退火温度和时间来控制，因此薄膜的性能可以相对自由地调整，正如这里通过电子显微镜和拉曼散射所证明的那样。我们表明纳米微晶尺寸和晶界的体积分数通过非线性光学和热过程在耗散率中起着关键作用。在 950°C 退火产生的纳米晶硅中实现的光机械腔中发现了有希望的光学 (13,000) 和机械 (1700) 品质因数。通过内部间隙状态增强的吸收和复合率以及降低的热导率提高了在包括纳米机电系统 (NEMS)、声子激光和基于混沌的设备在内的应用中利用这些非线性效应的潜力。我们表明纳米微晶尺寸和晶界的体积分数通过非线性光学和热过程在耗散率中起着关键作用。在 950°C 退火产生的纳米晶硅中实现的光机械腔中发现了有希望的光学 (13,000) 和机械 (1700) 品质因数。通过内部间隙状态增强的吸收和复合率以及降低的热导率提高了在包括纳米机电系统 (NEMS)、声子激光和基于混沌的设备在内的应用中利用这些非线性效应的潜力。我们表明纳米微晶尺寸和晶界的体积分数通过非线性光学和热过程在耗散率中起着关键作用。在 950°C 退火产生的纳米晶 Si 中实现的光机械腔中发现了有希望的光学 (13,000) 和机械 (1700) 品质因数。通过内部间隙状态增强的吸收和复合率以及降低的热导率提高了在包括纳米机电系统 (NEMS)、声子激光和基于混沌的设备在内的应用中利用这些非线性效应的潜力。