We fabricated a monolayer graphene transistor device in the shape of the Hall-bar structure, which produced an exactly symmetric signal following the sample geometry. During electrical characterization, the device showed the standard integer quantum Hall effect of monolayer graphene except for a broader range of several quantum Hall plateaus corresponding to small filling factors in the electron region. We investigated this anomaly on the basis of localized states owing to the presence of possible electron traps, whose energy levels were estimated to be near the Dirac point. In particular, the inequality between the filling of electrons and holes was ascribed to the requirement of excess electrons to fill the trap levels. The relations between the quantum Hall plateau, Landau level, and filling factor were carefully analyzed to reveal the details of the localized states in this graphene device.

我们制造了霍尔棒结构形状的单层石墨烯晶体管器件，该器件根据样品的几何形状产生精确对称的信号。在电学表征期间，该器件显示了单层石墨烯的标准整数量子霍尔效应，除了与电子区域中较小填充因子相对应的几个量子霍尔平稳区的范围更广之外。由于存在可能的电子陷阱，我们根据局部状态研究了这种异常，其能量水平估计在狄拉克点附近。特别地，电子和空穴的填充之间的不平等归因于需要过量的电子来填充陷阱能级。量子霍尔高原，朗道能级之间的关系