Elucidating the effect of boundary curvature on the wrinkling of thin suspended films by theory and experiment

采用微波等离子体增强化学气相沉积法在Corning Lotus NXT玻璃衬底上制备了超薄纳米金刚石薄膜。我们通过直接飞秒激光写入图案化这些薄膜。我们意外地发现，在相对较低的激光脉冲能量下，可以在玻璃衬底和纳米金刚石薄膜之间形成纳米通道。在相对较高的激光脉冲能量下，可以去除部分薄膜，这是我们最初的目标。诸如聚焦离子束铣削和电子束光刻的技术目前用于制造通过复杂工艺密封的开放纳米通道。因此，通过这种传统方法制造基于纳米通道的器件是复杂的、昂贵的和耗时的，阻碍了该领域的进展。我们的纳米通道制造方法克服了这些问题，因此具有很高的影响潜力。我们进一步研究了我们的方法背后的机制，并证明了纳米通道通过制造纳米流体装置来传导水。专利将于2023年4月提交。同时，我们还发现了NCD薄膜在沉积后产生压缩应变，并通过基板蚀刻从玻璃基板上部分剥离的新现象。边界曲率被观察到发挥作用，在这些电影，这遵循我们的假设。然而，我们发现，基板蚀刻量也起着至关重要的作用。

We synthesized ultra-thin nanocrystalline diamond (NCD) films on Corning Lotus NXT glass substrates with microwave plasma-enhanced chemical vapor deposition. We patterned these films through direct femtosecond laser writing. We accidentally found that nanochannels could be made between the glass substrate and the nanocrystalline diamond film at relatively low laser pulse energies. At relatively high laser pulse energies, portions of the film could be removed, which was our initial goal. Techniques such as focused ion beam milling and electron-beam lithography are currently used to fabricate open nanochannels that are sealed by intricate processes. Manufacturing nanochannel-based devices by such traditional methods is therefore complex, expensive, and time-consuming, hindering progress in the field. Our method for nanochannel manufacturing overcomes such issues and consequently has a high-impact potential. We further investigated the mechanism behind our method and demonstrated that the nanochannels conduct water by fabricating a nanofluidic device. A patent will be filed in April 2023. Immediately after that, we will submit a manuscript to an international journal.In parallel, we also found new phenomena in the wrinkling of NCD films that are compressively strained after deposition and partly released from the glass substrate through substrate etching. Boundary curvature is observed to play a role in the wrinkling of these films, which follows our hypothesis. However, we found that the amount of substrate etched also plays a crucial role.