Institut for Electronic, Microelectronic and Nanotechnology, Centre National de la Recherche Scientifique, Villeneuve d'Ascq, France.
Transport at Nanoscale Interfaces Laboratory, Swiss Federal Laboratories for Materials Science and Technology (EMPA), Dübendorf, Switzerland.
Nanoscale. 2023 May 25;15(20):9203-9213. doi: 10.1039/d2nr06682c.
We report a study on the relationship between the structure and electron transport properties of nanoscale graphene/pentacene interfaces. We fabricated graphene/pentacene interfaces from 10 to 30 nm thick needle-like pentacene nanostructures down to two-three layer (2L-3L) dendritic pentacene islands, and we measured their electron transport properties by conductive atomic force microscopy (C-AFM). The energy barrier at the interfaces, , the energy position of the pentacene highest occupied molecular orbital (HOMO) with respect to the Fermi energy of graphene and the C-AFM metal tip was determined and discussed with an appropriate electron transport model (a double Schottky diode model and a Landauer-Buttiker model, respectively) taking into account the voltage-dependent charge doping of graphene. In both types of samples, the energy barrier at the graphene/pentacene interface is slightly larger than that at the pentacene/metal tip interface, resulting in 0.47-0.55 eV and 0.21-0.34 eV, respectively, for the 10-30 nm thick needle-like pentacene islands, and 0.92-1.44 eV and 0.67-1.05 eV, respectively, for the 2L-3L thick dendritic pentacene nanostructures. We attribute this difference to the molecular organization details of the pentacene/graphene heterostructures, with pentacene molecules lying flat on graphene in the needle-like pentacene nanostructures, while standing upright in the 2L-3L dendritic islands, as observed from Raman spectroscopy.
我们报告了一种关于纳米级石墨烯/并五苯界面结构与电子输运性质关系的研究。我们制备了厚度从 10 到 30nm 的针状并五苯纳米结构至 2-3 层（2L-3L）树枝状并五苯岛的石墨烯/并五苯界面，并通过导电原子力显微镜（C-AFM）测量了它们的电子输运性质。界面处的能垒，，相对于石墨烯费米能级的并五苯最高占据分子轨道（HOMO）的能量位置和 C-AFM 金属探针，用适当的电子输运模型（双肖特基二极管模型和兰道尔-布特克尔模型，分别）进行了确定和讨论，考虑到石墨烯的电压相关电荷掺杂。在这两种类型的样品中，石墨烯/并五苯界面的能垒略大于并五苯/金属探针界面的能垒，导致厚度为 10-30nm 的针状并五苯岛分别为 0.47-0.55eV 和 0.21-0.34eV，而 2L-3L 厚的树枝状并五苯纳米结构分别为 0.92-1.44eV 和 0.67-1.05eV。我们将这种差异归因于并五苯/石墨烯异质结构的分子组织细节，在针状并五苯纳米结构中， 并五苯分子在石墨烯上平躺，而在 2L-3L 树枝状岛屿中， 并五苯分子直立，这是从拉曼光谱中观察到的。
