Bejing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University , Beijing 100871, P. R. China.
Academy for Advanced Interdisciplinary Studies, Peking University , Beijing 100871, China.
ACS Nano. 2017 May 23;11(5):4641-4650. doi: 10.1021/acsnano.7b00313. Epub 2017 May 4.
Graphitic nitrogen-doped graphene is an excellent platform to study scattering processes of massless Dirac Fermions by charged impurities, in which high mobility can be preserved due to the absence of lattice defects through direct substitution of carbon atoms in the graphene lattice by nitrogen atoms. In this work, we report on electrical and magnetotransport measurements of high-quality graphitic nitrogen-doped graphene. We show that the substitutional nitrogen dopants in graphene introduce atomically sharp scatters for electrons but long-range Coulomb scatters for holes and, thus, graphitic nitrogen-doped graphene exhibits clear electron-hole asymmetry in transport properties. Dominant scattering processes of charge carriers in graphitic nitrogen-doped graphene are analyzed. It is shown that the electron-hole asymmetry originates from a distinct difference in intervalley scattering of electrons and holes. We have also carried out the magnetotransport measurements of graphitic nitrogen-doped graphene at different temperatures and the temperature dependences of intervalley scattering, intravalley scattering, and phase coherent scattering rates are extracted and discussed. Our results provide an evidence for the electron-hole asymmetry in the intervalley scattering induced by substitutional nitrogen dopants in graphene and shine a light on versatile and potential applications of graphitic nitrogen-doped graphene in electronic and valleytronic devices.
石墨型氮掺杂石墨烯是研究无质量狄拉克费米子在带电杂质散射过程的理想平台，由于氮原子直接取代石墨烯晶格中的碳原子，晶格缺陷得以避免，因此其具有很高的迁移率。在这项工作中，我们报告了高质量石墨型氮掺杂石墨烯的电学和磁输运测量结果。我们发现，石墨烯中的取代型氮掺杂原子对电子产生原子级尖锐散射，但对空穴产生长程库仑散射，因此，石墨型氮掺杂石墨烯在输运性质上表现出明显的电子-空穴不对称性。分析了载流子在石墨型氮掺杂石墨烯中的主要散射过程。结果表明，电子-空穴不对称性源于电子和空穴的谷间散射的明显差异。我们还在不同温度下对石墨型氮掺杂石墨烯进行了磁输运测量，并提取和讨论了谷间散射、谷内散射和相位相干散射率随温度的变化关系。我们的结果为石墨烯中取代型氮掺杂引起的谷间散射中的电子-空穴不对称性提供了证据，并为电子和谷电子器件中石墨型氮掺杂石墨烯的多种潜在应用提供了思路。
