碳化硅衬底上外延双层石墨烯的电输运性质  

Electron transport property of epitaixial bilayer graphene on SiC substrate

作　　者：胡聚罡 贾振宇 李绍春 Hu Ju-Gang;Jia Zhen-Yu;Li Shao-Chun(National Laboratory of Solid State Microstructures,School of Physics,Nanjing University,Nanjing 210093,China;Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China;Shanghai Tianma Micro-electronics,Shanghai 201201,China)

机构地区：[1]南京大学物理学院,固体微结构物理国家重点实验室,南京210093 [2]南京大学人工微结构科学与技术协同创新中心,南京210093 [3]上海天马微电子有限公司,上海201201

出　　处：《物理学报》2022年第12期204-210,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11774149,11790311,92165205);国家重点研发计划(批准号:2021YFA1400403)资助的课题。

摘　　要：石墨烯是低维材料领域研究的热点,在这一体系中研究发现了诸多新奇的量子现象,深入理解石墨烯的电输运性质对于其在未来电子学器件中的应用具有重要的意义.本文通过热分解的方法在SiC单晶衬底上获得外延的双层石墨烯,并系统研究了其电输运性质.在小磁场范围内观测到弱局域化效应,并在较大的磁场区间发现了不饱和线性磁阻.通过角度依赖的磁阻测量,发现该线性磁阻现象符合二维体系的磁输运特征.还在平行场下观测到了负磁阻效应,可能是由双层石墨烯的转角莫尔条纹导致的局部晶格起伏导致的.本文工作加深了对于外延生长的层间具有一定转角的双层石墨烯的电输运性质的认识.Graphene can find great potential applications in the future electronic devices. In bilayer graphene, the relative rotation angle between graphene layers can modulate the interlayer interaction and hence induces rich physical phenomena. We systematically study the temperature dependent magnetoresistance(MR) properties in the epitaxial bilayer graphene(BLG) grown on the SiC substrate. High quality BLG is synthesized by molecular beam epitaxy in ultra-high vacuum. We observe the negative MR under a small magnetic field applied perpendicularly at temperature < 80 K, which is attributed to a weak localization effect. The weak localization effect in our epitaxial BLG is stronger than previously reported ones in epitaxial monolayer and multilayer graphene system, which is possibly because of the enhanced interlayer electron transition and thus the enhanced valley scattering in the BLG. As the magnetic field increases, the MR exhibits a classical Lorentz MR behavior.Moreover, we observe a linear magnetoresistance behavior in a large field, which shows no saturation for the magnetic field of up to 9 T. In order to further investigate the negative and linear magnetoresistance, we conduct angle-dependent magnetoresistance measurements, which indicates the two-dimensional magnetotransport phenomenon. We also find that the negative MR phenomenon occurs under a parallel magnetic field,which may correspond to the moiré pattern induced local lattice fluctuation as demonstrated by scanning tunneling microscopy measurement on an atomic scale. Our work paves the way for investigating the intrinsic properties of epitaxial BLG under various conditions.

关 键 词：外延双层石墨烯 磁电阻 负磁阻 扫描隧道显微镜 

分 类 号：TQ127.11[化学工程—无机化工]