Negative magnetoresistance in Ti-cleaned single-layer graphene

International Workshop on Dirac Electrons in Solids 2015

Fujimoto, A.^1 ; Joiner, C.A.^2 ; Jiang, Y.^3 ; Terasawa, D.^4 ; Fukuda, A.^4 ; Jiang, Z.^3 ; Vogel, E.M.^2

Applied Physics, Osaka Institute of Technology, Osaka, Japan^1

School of Materials Science and Engineering, Georgia Tech, Atlanta

GA, United States^2

School of Physics, Georgia Tech, Atlanta

GA, United States^3

Department of Physics, Hyogo College of Medicine, Hyogo, Nishinomiya, Japan^4

关键词: Back-gate voltages;    Chemical vapor deposited;    Electron-hole puddles;    Fabrication process;    Negative magneto-resistance;    Potential barriers;    Resonant tunneling device;    Theoretical formulation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/603/1/012021/pdf
DOI  :  10.1088/1742-6596/603/1/012021

来源: IOP

【 摘 要 】

Symmetric graphene tunnelingfield-effect transistors (SymFETs) consisting of two independently gated graphene layers separated by a potential barrier have been proposed as a room-temperature resonant tunneling device. In a SymFET, the inelastic-coherent length (Lφ) of the electrons is considered to be one of the important characteristic scattering lengths. Weak localization (WL) is a good tool to estimate LφIn this study, the surface of the chemical-vapor- deposited single-layer graphene was Ticleaned after performing the conventional fabrication processes for graphene transistors. We found that the charge-neutral point (VCNP) shifted to a lower back-gate voltage and the mobility increased owing to Ticleaning. Ti-cleaned Hall bars were investigated at 0.3 K under magnetic fields of up to 14 T. Negative magnetoresistance(MR) appears because of the WL effect, and the MR increases as the back-gate voltage (VG) approaches VCNP. From a fitting analysis using the theoretical formulation of WL, we found that Lφwas greater than 100 nm and that LPdecreased as VGapproached VCNPbecause of electron-hole puddles and electron-electron interaction.