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技术在康宁莲花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的方式制作了这些薄膜的图案。我们偶然发现，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。聚焦离子束研磨和电子束光刻等技术目前被用来制造通过复杂工艺密封的开放纳米通道。因此，用这种传统方法制造基于纳米通道的器件是复杂、昂贵和耗时的，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方法背后的机制，并证明了纳米通道通过制造纳米流体器件来传导水。专利将于2023年4月提交。随后，我们将立即向一家国际期刊提交稿件。同时，我们还发现了NCD薄膜在沉积后被压缩应变并通过基板腐蚀部分从玻璃基板上释放出来的新现象。观察到边界曲率在这些薄膜的褶皱中起作用，这符合我们的假设。然而，我们发现衬底的刻蚀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.