Homogeneous, single-crystal, monolayer epitaxial graphene (EG) is the one of most promising candidates for the advancement of quantized Hall resistance (QHR) standards. A remaining challenge for the electrical characterization of EG-based quantum Hall devices as a useful tool for metrology is that they are electrically unstable when exposed to air due to the adsorption of and interaction with atmospheric molecular dopants. The resulting changes in the charge carrier density become apparent by variations in the surface conductivity, the charge carrier mobility, and may result in a transition from n-type to p-type conductivity. This work evaluates the use of Parylene C and Parylene N as passivation layers for EG. Electronic transport of EG quantum Hall devices and non-contact microwave perturbation measurements of millimeter-sized areas of EG are both performed on bare and Parylene coated samples to test the efficacy of the passivation layers. The reported results, showing a significant improvement in passivation due to Parylene deposition, suggest a method for the mass production of millimeter-scale graphene devices with stable electrical properties.

中文翻译：

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使用聚对二甲苯钝化检查外延石墨烯表面电导率和量子霍尔器件稳定性


均质、单晶、单层外延石墨烯（EG）是推动量子霍尔电阻（QHR）标准最有希望的候选材料之一。作为一种有用的计量工具，基于 EG 的量子霍尔器件的电学特性面临的一个挑战是，当它们暴露在空气中时，由于大气分子掺杂剂的吸附和相互作用，其电学不稳定。电荷载流子密度的变化通过表面电导率、载流子迁移率的变化而变得明显，并且可能导致从n型导电性转变为p型导电性。这项工作评估了聚对二甲苯 C 和聚对二甲苯 N 作为 EG 钝化层的使用。 EG 量子霍尔器件的电子传输和毫米级 EG 区域的非接触式微波微扰测量均在裸露样品和聚对二甲苯涂层样品上进行，以测试钝化层的功效。报告的结果显示，由于聚对二甲苯沉积，钝化效果显着改善，这提出了一种大规模生产具有稳定电性能的毫米级石墨烯器件的方法。