National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA.
Nanoscale. 2017 Aug 17;9(32):11537-11544. doi: 10.1039/c7nr04155a.
Atmospheric chemical doping can be used to modify the electronic properties of graphene. Here we report that the chemical atmospheric doping (derived from air, oxygen and water vapor) of low-carrier-density monolayer epitaxial graphene on SiC can be readily tuned by a simple low-temperature (T ≤ 450 K), in situ vacuum gentle heating method. Interestingly, such an approach allows, for the first time, the observation of a crossover from graphene (μ/μ ≈ 2) to an "ordinary metal" (μ/μ ≈ 1) with decreasing carrier density, where μ and μ are transport mobility and quantum mobility, respectively. In the low carrier density limit, our results are consistent with the theoretical prediction that μ is inversely proportional to charged impurity density. Our data also suggest that atmospheric chemical doping can be used to vary intervalley scattering in graphene which plays a crucial role in backward scattering events.
大气化学掺杂可用于修饰石墨烯的电子性质。在这里，我们报告了通过简单的低温（T≤450 K）、原位真空温和加热方法，可以很容易地调节 SiC 上低载流子密度单层外延石墨烯的化学大气掺杂（源自空气、氧气和水蒸气）。有趣的是，这种方法首次允许观察到从石墨烯（μ/μ≈2）到“普通金属”（μ/μ≈1）的转变，载流子密度降低，其中μ和μ分别是迁移率和量子迁移率。在低载流子密度极限下，我们的结果与理论预测一致，即μ与带电杂质密度成反比。我们的数据还表明，大气化学掺杂可用于改变石墨烯中的谷间散射，这在反向散射事件中起着至关重要的作用。
