Cara Eleonora, Ferrarese Lupi Federico, Fretto Matteo, De Leo Natascia, Tortello Mauro, Gonnelli Renato, Sparnacci Katia, Boarino Luca
Advanced Materials Metrology and Life Sciences Division, Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy.
Dipartimento di Scienza Applicata e Tecnologia (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
Nanomaterials (Basel). 2020 Feb 7;10(2):280. doi: 10.3390/nano10020280.
In this work, we performed a systematic study on the effect of the geometry of pre-patterned templates and spin-coating conditions on the self-assembling process of colloidal nanospheres. To achieve this goal, large-scale templates, with different size and shape, were generated by direct laser-writer lithography over square millimetre areas. When deposited over patterned templates, the ordering dynamics of the self-assembled nanospheres exhibits an inverse trend with respect to that observed for the maximisation of the correlation length ξ on a flat surface. Furthermore, the self-assembly process was found to be strongly dependent on the height (H) of the template sidewalls. In particular, we observed that, when H is 0.6 times the nanospheres diameter and spinning speed 2500 rpm, the formation of a confined and well ordered monolayer is promoted. To unveil the defects generation inside the templates, a systematic assessment of the directed self-assembly quality was performed by a novel method based on Delaunay triangulation. As a result of this study, we found that, in the best deposition conditions, the self-assembly process leads to well-ordered monolayer that extended for tens of micrometres within the linear templates, where 96.2% of them is aligned with the template sidewalls.
在这项工作中，我们对预图案化模板的几何形状和旋涂条件对胶体纳米球自组装过程的影响进行了系统研究。为实现这一目标，通过直接激光写入光刻技术在平方毫米区域上生成了具有不同尺寸和形状的大规模模板。当沉积在图案化模板上时，自组装纳米球的有序动力学相对于在平坦表面上观察到的相关长度ξ最大化时呈现出相反的趋势。此外，发现自组装过程强烈依赖于模板侧壁的高度（H）。特别是，我们观察到，当H为纳米球直径的0.6倍且旋转速度为2500转/分钟时，促进了受限且有序的单层的形成。为了揭示模板内部的缺陷产生情况，通过一种基于德劳内三角剖分的新方法对定向自组装质量进行了系统评估。作为这项研究的结果，我们发现，在最佳沉积条件下，自组装过程导致形成在线性模板内延伸数十微米的有序单层，其中96.2%与模板侧壁对齐。
