Quantum Transport and Field-Induced Insulating States in Bilayer Graphene pnp Junctions
详细信息 查看全文
- 作者：Lei Jing ; Jairo Velasco Jr. ; Philip Kratz ; Gang Liu ; Wenzhong Bao ; Marc Bockrath ; Chun Ning Lau
- 刊名：Nano Letters
- 出版年：2010
- 出版时间：October 13, 2010
- 年：2010
- 卷：10
- 期：10
- 页码：4000-4004
- 全文大小：318K
- 年卷期：v.10,no.10(October 13, 2010)
- ISSN：1530-6992
文摘
We perform transport measurements in high quality bilayer graphene pnp junctions with suspended top gates. At a magnetic field B = 0, we demonstrate band gap opening by an applied perpendicular electric field with an On/Off ratio up to 20000 at 260 mK. Within the band gap, the conductance decreases exponentially by 3 orders of magnitude with increasing electric field and can be accounted for by variable range hopping with a gate-tunable density of states, effective mass, and localization length. At large B, we observe quantum Hall conductance with fractional values, which arise from equilibration of edge states between differentially doped regions, and the presence of an insulating state at filling factor v = 0. Our work underscores the importance of bilayer graphene for both fundamental interest and technological applications.