Darawish Rimah, Braun Oliver, Müllen Klaus, Calame Michel, Ruffieux Pascal, Fasel Roman, Borin Barin Gabriela
Empa, Swiss Federal Laboratories for Materials Science and Technology, Nanotech@surfaces Laboratory 8600 Dübendorf Switzerland
Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern 3012 Bern Switzerland.
Nanoscale Adv. 2025 Feb 11;7(7):1962-1971. doi: 10.1039/d5na00017c. eCollection 2025 Mar 25.
Graphene nanoribbons (GNRs) with atomically precise widths and edge topologies have well-defined band gaps that depend on ribbon dimensions, making them ideal for room-temperature switching applications like field-effect transistors (FETs). For effective device integration, it is crucial to optimize growth conditions to maximize GNR length and, consequently, device yield. Equally important is establishing device integration and monitoring strategies that maintain GNR quality during the transition from growth to device fabrication. Here, we investigate the growth and alignment of 9-atom-wide armchair graphene nanoribbons (9-AGNRs) on a vicinal gold substrate, Au(788), with varying molecular precursor doses (PD) and, therefore, different resulting GNR coverages. Our investigation reveals that GNR growth location on Au(788) substrate is coverage-dependent. Scanning tunneling microscopy shows a strong correlation between GNR length evolution and both PD and GNR growth location. Employing Raman spectroscopy, samples with eight different PDs were analyzed. GNR alignment improves with length, achieving near-perfect alignment with an average length of ∼40 nm for GNRs growing solely at the Au(788) step edges. To fully exploit GNR properties in device architectures, GNRs need to be transferred from their metallic growth substrate to semiconducting or insulating substrates. Upon transfer, samples with higher PD present systematically better alignment preservation and less surface disorder, attributed to reduced GNR mobility during the transfer process. Importantly, PD also affects the substrate transfer success rate, with higher success rates observed for samples with higher GNR coverages (77%) compared to lower GNR coverages (53%). Our findings characterize the important relationship between precursor dose, GNR length, alignment quality, and surface disorder during GNR growth and upon substrate transfer, offering crucial insights for the further development of GNR-based nanoelectronic devices.
具有原子级精确宽度和边缘拓扑结构的石墨烯纳米带（GNRs）具有明确的带隙，该带隙取决于纳米带的尺寸，这使其成为场效应晶体管（FET）等室温开关应用的理想选择。为了实现有效的器件集成，优化生长条件以最大化GNR长度并因此提高器件产量至关重要。同样重要的是建立器件集成和监测策略，以在从生长到器件制造的过渡过程中保持GNR的质量。在这里，我们研究了在具有不同分子前驱体剂量（PD）以及因此不同GNR覆盖率的近邻金衬底Au(788)上9原子宽扶手椅型石墨烯纳米带（9-AGNRs）的生长和排列情况。我们的研究表明，GNR在Au(788)衬底上的生长位置取决于覆盖率。扫描隧道显微镜显示GNR长度演变与PD以及GNR生长位置之间存在很强的相关性。利用拉曼光谱对具有八个不同PD的样品进行了分析。GNR的排列随长度增加而改善，对于仅在Au(788)台阶边缘生长的GNR，平均长度约为40 nm时可实现近乎完美的排列。为了在器件架构中充分利用GNR的特性，需要将GNR从其金属生长衬底转移到半导体或绝缘衬底上。转移后，具有较高PD的样品表现出系统上更好的排列保留和更少的表面无序，这归因于转移过程中GNR迁移率的降低。重要的是，PD还会影响衬底转移成功率，与较低GNR覆盖率（53%）的样品相比，较高GNR覆盖率（77%）的样品观察到更高的成功率。我们的研究结果表征了GNR生长过程中以及衬底转移后前驱体剂量、GNR长度、排列质量和表面无序之间的重要关系，为基于GNR的纳米电子器件的进一步发展提供了关键见解。
