Ribeiro-Palau Rebeca, Chen Shaowen, Zeng Yihang, Watanabe Kenji, Taniguchi Takashi, Hone James, Dean Cory R
Department of Physics , Columbia University , New York , New York 10027 , United States.
Department of Mechanical Engineering , Columbia University , New York , New York 10027 , United States.
Nano Lett. 2019 Apr 10;19(4):2583-2587. doi: 10.1021/acs.nanolett.9b00351. Epub 2019 Mar 8.
Realizing graphene's promise as an atomically thin and tunable platform for fundamental studies and future applications in quantum transport requires the ability to electrostatically define the geometry of the structure and control the carrier concentration, without compromising the quality of the system. Here, we demonstrate the working principle of a new generation of high-quality gate-defined graphene samples, where the challenge of doing so in a gapless semiconductor is overcome by using the ν = 0 insulating state, which emerges at modest applied magnetic fields. In order to verify that the quality of our devices is not compromised, we compare the electronic transport response of different sample geometries, paying close attention to fragile quantum states, such as the fractional quantum Hall states that are highly susceptible to disorder. The ability to define local depletion regions without compromising device quality establishes a new approach toward structuring graphene-based quantum transport devices.
要实现石墨烯作为一种原子级薄且可调节的平台在基础研究和量子输运未来应用中的潜力，需要能够在不影响系统质量的情况下，通过静电作用定义结构的几何形状并控制载流子浓度。在此，我们展示了新一代高质量栅极定义石墨烯样品的工作原理，其中通过利用在适度施加磁场时出现的ν = 0绝缘态，克服了在无隙半导体中这样做的挑战。为了验证我们器件的质量未受影响，我们比较了不同样品几何形状的电子输运响应，密切关注脆弱的量子态，例如对无序高度敏感的分数量子霍尔态。在不影响器件质量的情况下定义局部耗尽区的能力，为构建基于石墨烯的量子输运器件建立了一种新方法。
