Preischl Christian, Le Linh Hoang, Bilgilisoy Elif, Gölzhäuser Armin, Marbach Hubertus
Physikalische Chemie II, Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany.
Beilstein J Nanotechnol. 2021 Apr 7;12:319-329. doi: 10.3762/bjnano.12.26. eCollection 2021.
Focused electron beam-induced processing is a versatile method for the fabrication of metallic nanostructures with arbitrary shape, in particular, on top of two-dimensional (2D) organic materials, such as self-assembled monolayers (SAMs). Two methods, namely electron beam-induced deposition (EBID) and electron beam-induced surface activation (EBISA) are studied with the precursors Fe(CO) and Co(CO)NO on SAMs of 1,1',4',1''-terphenyl-4-thiol (TPT). For Co(CO)NO only EBID leads to deposits consisting of cobalt oxide. In the case of Fe(CO) EBID and EBISA yield deposits consisting of iron nanocrystals with high purity. Remarkably, the EBISA process exhibits a strong time dependence, which is analyzed in detail for different electron doses. This time dependence is a new phenomenon, which, to the best of our knowledge, was not reported before. The electron-induced cross-linking of the SAM caused by the cleavage of C-H bonds and the subsequent formation of new C-C bonds between neighboring molecules also seems to play a crucial role in the EBISA process. Previous studies showed that iron nanostructures fabricated on top of a cross-linked SAM on Au/mica can be transferred to solid substrates and grids without any changes, aside from oxidation. Here we demonstrate that iron as well as cobalt oxide structures on top of a cross-linked SAM on Ag/mica do change more significantly. The Fe(NO) solution used for etching of the Ag layer also dissolves the cobalt oxide structures and causes dissolution and reduction of the iron structures. These results demonstrate that the fabrication of hybrids of metallic nanostructures onto organic 2D materials is an intrinsically complex procedure. The interactions among the metallic deposits, the substrate for the growth of the SAM, and the associated etching/dissolving agent need to be considered and further studied.
聚焦电子束诱导加工是一种用于制造任意形状金属纳米结构的通用方法，特别是在二维（2D）有机材料（如自组装单分子层（SAMs））上制造。研究了两种方法，即电子束诱导沉积（EBID）和电子束诱导表面活化（EBISA），使用前驱体Fe(CO)₅和Co(CO)₃NO在1,1',4',1''-四联苯-4-硫醇（TPT）的SAMs上进行。对于Co(CO)₃NO，只有EBID会产生由氧化钴组成的沉积物。在Fe(CO)₅的情况下，EBID和EBISA产生的沉积物由高纯度的铁纳米晶体组成。值得注意的是，EBISA过程表现出强烈的时间依赖性，针对不同电子剂量进行了详细分析。这种时间依赖性是一种新现象，据我们所知，之前尚未有报道。由C-H键断裂引起的SAM的电子诱导交联以及相邻分子之间随后形成的新C-C键似乎在EBISA过程中也起着关键作用。先前研究表明，在Au/云母上的交联SAM顶部制造的铁纳米结构除了氧化外，可以无任何变化地转移到固体基板和网格上。在这里，我们证明在Ag/云母上的交联SAM顶部的铁以及氧化钴结构变化更为显著。用于蚀刻Ag层的Fe(NO₃)₃溶液也会溶解氧化钴结构，并导致铁结构的溶解和还原。这些结果表明，在有机二维材料上制造金属纳米结构的杂化物是一个本质上复杂的过程。需要考虑并进一步研究金属沉积物、SAM生长的基板以及相关蚀刻/溶解剂之间的相互作用。
