A beam of holes formed in graphene by a collimating contact is imaged using a liquid-He cooled scanning probe microscope (SPM). The mean free path of holes is greater than the device dimensions. A zigzag shaped pattern on both sides of the collimating contact absorb holes that enter at large angles. The image charge beneath the SPM tip defects holes, and the pattern of flow is imaged by displaying the change in conductance between contacts on opposite sides, as the tip is raster scanned across the sample. Collimation is confirmed by bending hole trajectories away from the receiving contact with an applied magnetic field. The SPM images agree well with ray-tracing simulations.

中文翻译：

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成像来自石墨烯准直接触的空穴流

使用液氦冷却扫描探针显微镜 (SPM) 对通过准直接触在石墨烯中形成的孔束进行成像。孔的平均自由程大于器件尺寸。准直触点两侧的锯齿形图案吸收以大角度进入的孔。SPM 尖端下方的图像电荷缺陷孔，以及流动模式通过显示相对侧触点之间的电导变化来成像，因为尖端在样品上进行光栅扫描。通过外加磁场使孔轨迹远离接收触点弯曲来确认准直。SPM 图像与光线追踪模拟非常吻合。