Rigosi Albert F, Glavin Nicholas R, Liu Chieh-I, Yang Yanfei, Obrzut Jan, Hill Heather M, Hu Jiuning, Lee Hsin-Yen, Hight Walker Angela R, Richter Curt A, Elmquist Randolph E, Newell David B
National Institute of Standards and Technology (NIST), 100 Bureau Drive, Gaithersburg, MD, 20899, USA.
Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH, 45433, USA.
Small. 2017 Jul;13(26). doi: 10.1002/smll.201700452. Epub 2017 May 19.
Regarding the improvement of current quantized Hall resistance (QHR) standards, one promising avenue is the growth of homogeneous monolayer epitaxial graphene (EG). A clean and simple process is used to produce large, precise areas of EG. Properties like the surface conductivity and dielectric loss tangent remain unstable when EG is exposed to air due to doping from molecular adsorption. Experimental results are reported on the extraction of the surface conductivity and dielectric loss tangent from data taken with a noncontact resonance microwave cavity, assembled with an air-filled, standard R100 rectangular waveguide configuration. By using amorphous boron nitride (a-BN) as an encapsulation layer, stability of EG's electrical properties under ambient laboratory conditions is greatly improved. Moreover, samples are exposed to a variety of environmental and chemical conditions. Both thicknesses of a-BN encapsulation are sufficient to preserve surface conductivity and dielectric loss tangent to within 10% of its previously measured value, a result which has essential importance in the mass production of millimeter-scale graphene devices demonstrating electrical stability.
关于当前量子化霍尔电阻（QHR）标准的改进，一个有前景的途径是生长均匀的单层外延石墨烯（EG）。采用一种清洁且简单的工艺来制备大面积、精确的EG区域。当EG暴露于空气中时，由于分子吸附导致的掺杂，其表面电导率和介电损耗角正切等性质会保持不稳定。本文报道了利用一个与充满空气的标准R100矩形波导配置组装的非接触共振微波腔所采集的数据来提取表面电导率和介电损耗角正切的实验结果。通过使用非晶态氮化硼（a-BN）作为封装层，EG在实验室环境条件下的电学性质稳定性得到了极大提高。此外，样品还暴露于各种环境和化学条件下。两种厚度的a-BN封装都足以将表面电导率和介电损耗角正切保持在其先前测量值的10%以内，这一结果对于展示电稳定性的毫米级石墨烯器件的大规模生产至关重要。
