Orsini Andrea, Falconi Christian
Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy.
Facoltà di Ingegneria, Università degli Studi Niccolò Cusano, Via Don Carlo Gnocchi 3, 00166 Rome, Italy.
ACS Appl Nano Mater. 2022 Oct 28;5(10):15817-15825. doi: 10.1021/acsanm.2c03963. Epub 2022 Sep 28.
The fabrication of devices with accurately controlled properties almost invariably takes advantage of feedback so that, based on real-time measurements, process parameters can be automatically adjusted in order to obtain the desired characteristics. Nevertheless, despite the outstanding advantages of wet-chemistry methods (e.g., simplicity, low-cost, low-temperature, and compatibility with almost any process and type of substrate), the use of feedback in the solution growth of nanostructures is almost unexplored. In fact, conventional techniques for the real-time in-liquid characterization of nanostructures are extremely complex and can introduce intricate artefacts. Here, by taking advantage of an electro-mechanical resonator as a substrate, we on-line monitor, at the system level, the nanostructure growth, thus enabling the feedback-assisted tuning of low-cost electro-mechanical resonators by ZnO nanowires. This approach allows for post-fabrication tuning of the resonant frequency with high accuracy and high tuning range (e.g., about 1% in our experiments) in a simple, fast, low power, and low-cost manner, without requiring expensive facilities such as clean rooms or high-vacuum deposition systems. Moreover, remarkably, we find that for a given desired resonant frequency, the quality factor of the resonance can be separately adjusted by modifying the nutrient solution, which can be a key advantage for filters. The straightforward interfacing and packaging of the final resonator stems from the large difference, about 5 orders of magnitude, between the key structure dimensions, namely, the diameter of the ZnO nanowires and the much larger (e.g., few millimeters) diameter of the quartz. Our results can lead to the widespread application of nanowire-tuned electro-mechanical oscillators and filters in electronics, sensors, and material science.
制造具有精确可控特性的器件几乎总是要利用反馈，以便根据实时测量结果自动调整工艺参数，从而获得所需的特性。然而，尽管湿化学方法具有显著优势（例如，简单、低成本、低温以及与几乎任何工艺和衬底类型兼容），但在纳米结构的溶液生长中使用反馈的情况几乎未被探索。事实上，用于纳米结构实时液体表征的传统技术极其复杂，并且可能会引入复杂的伪像。在这里，通过利用机电谐振器作为衬底，我们在系统层面在线监测纳米结构的生长，从而实现通过氧化锌纳米线对低成本机电谐振器进行反馈辅助调谐。这种方法允许以简单、快速、低功耗和低成本的方式对谐振频率进行高精度和高调谐范围（例如，在我们的实验中约为1%）的后制造调谐，而无需诸如洁净室或高真空沉积系统等昂贵设施。此外，值得注意的是，我们发现对于给定的所需谐振频率，可以通过修改营养液来单独调整共振的品质因数，这对于滤波器来说可能是一个关键优势。最终谐振器的直接接口和封装源于关键结构尺寸之间大约5个数量级的巨大差异，即氧化锌纳米线的直径与石英大得多（例如，几毫米）的直径之间的差异。我们的结果可能会导致纳米线调谐的机电振荡器和滤波器在电子、传感器和材料科学中的广泛应用。
