Department of Physics, University of South Florida , Tampa, Florida 33620, United States.
ACS Appl Mater Interfaces. 2015 Jan 28;7(3):2082-7. doi: 10.1021/am508154n. Epub 2015 Jan 15.
Integrating graphene into nanoelectronic device structure requires interfacing graphene with high-κ dielectric materials. However, the dewetting and thermal instability of dielectric layers on top of graphene makes fabricating a pinhole-free, uniform, and conformal graphene/dielectric interface challenging. Here, we demonstrate that an ultrathin layer of high-κ dielectric material Y2O3 acts as an effective seeding layer for atomic layer deposition of Al2O3 on graphene. Whereas identical Al2O3 depositions lead to discontinuous film on bare graphene, the Y2O3 seeding layer yields uniform and conformal films. The morphology of the Al2O3 film is characterized by atomic force microscopy and transmission electron microscopy. C-1s X-ray photoemission spectroscopy indicates that the underlying graphene remains intact following Y2O3 seed and Al2O3 deposition. Finally, photoemission measurements of the graphene/SiO2/Si, Y2O3/graphene/SiO2, and Al2O3/Y2O3/graphene/SiO2 interfaces indicate n-type doping of graphene with different doping levels due to charge transfer at the interfaces.
将石墨烯整合到纳米电子器件结构中需要将石墨烯与高介电常数介电材料相连接。然而，在石墨烯顶部的介电层会发生去湿和热不稳定性，这使得制造无针孔、均匀且保形的石墨烯/介电界面具有挑战性。在这里，我们证明了一层超薄的高介电常数材料 Y2O3 可以作为原子层沉积在石墨烯上的 Al2O3 的有效成核层。虽然相同的 Al2O3 沉积会导致在裸石墨烯上形成不连续的薄膜，但 Y2O3 成核层会产生均匀且保形的薄膜。通过原子力显微镜和透射电子显微镜对 Al2O3 薄膜的形貌进行了表征。C-1s X 射线光电子能谱表明，在 Y2O3 种子和 Al2O3 沉积后，底层石墨烯保持完整。最后，对石墨烯/SiO2/Si、Y2O3/石墨烯/SiO2 和 Al2O3/Y2O3/石墨烯/SiO2 界面的光发射测量表明，由于界面处的电荷转移，石墨烯表现出不同掺杂水平的 n 型掺杂。
