Max Planck Institute for Solid State Research, Stuttgart, Germany.
Nano Lett. 2010 Apr 14;10(4):1149-53. doi: 10.1021/nl903162a.
The intrinsic doping level of graphene prepared by mechanical exfoliation and standard lithography procedures on thermally oxidized silicon varies significantly and seems to depend strongly on processing details and the substrate morphology. Moreover, transport properties of such graphene devices suffer from hysteretic behavior under ambient conditions. The hysteresis presumably originates from dipolar adsorbates on the substrate or graphene surface. Here, we demonstrate that it is possible to reliably obtain low intrinsic doping levels and to strongly suppress hysteretic behavior even in ambient air by depositing graphene on top of a thin, hydrophobic self-assembled layer of hexamethyldisilazane (HMDS). The HMDS serves as a reproducible template that prevents the adsorption of dipolar substances. It may also screen the influence of substrate deficiencies.
通过机械剥落和标准光刻工艺在热氧化硅上制备的石墨烯的本征掺杂水平变化很大，似乎强烈依赖于处理细节和衬底形貌。此外，这种石墨烯器件的传输性能在环境条件下表现出滞后行为。这种滞后可能源于衬底或石墨烯表面上的偶极吸附物。在这里，我们证明了通过在薄的疏水性自组装层六甲基二硅氮烷（HMDS）上沉积石墨烯，有可能可靠地获得低本征掺杂水平，并在环境空气中强烈抑制滞后行为。HMDS 用作可重复的模板，可防止偶极物质的吸附。它还可能屏蔽衬底缺陷的影响。
