论文标题
远程自由载体筛选，以提高Fröhlich-Limimimit 2D半导体的移动性
Remote free-carrier screening to boost the mobility of Fröhlich-limited 2D semiconductors
论文作者
论文摘要
Van der waals异质结构提供了一种多功能工具，不仅可以保护或控制，还可以增强2D材料的特性。我们使用从头算计算和半分析模型来找到策略，从而提高了异质结构中携带2D半导体的活动性。来自金属“筛选器”层的自由载体筛选远程抑制电流携带层中的电子 - phonon相互作用。这个概念在2D半导体中最有效，这些半导体的散射是由可筛选的电子 - 音波相互作用所支配的，尤其是fröhlich耦合到极性光子声子。这样的材料是常见的，其特征是在小掺杂极限中的总体低迁移率，而当2D材料的掺杂到足以通过其自由载体筛选的电子相互作用时，较高的材料则更高。我们将GASE用作原型，并将其放在带有掺杂石墨烯的异质结构中，作为“筛选器”层，而BN作为分离器。我们通过结合在密度官能扰动理论中计算的单个层的响应来开发一种方法来确定任何异质结构的静电响应。从石墨烯进行远程筛选可以抑制长波长的fröhlich互动，从而使Gase的运营商密度从$ 10^{11} $ $ 10^{11}到$ 10^{13} $ CM $^{ - $ CM $^{ - 2} $。值得注意的是，低兴奋剂的迁移率通过因子2.5增强。这种远程自由载体筛选比对介电环境的更常规操作更有效，当分离器（BN）薄时，最有效。
Van der Waals heterostructures provide a versatile tool to not only protect or control, but also enhance the properties of a 2D material. We use ab initio calculations and semi-analytical models to find strategies which boost the mobility of a current-carrying 2D semiconductor within an heterostructure. Free-carrier screening from a metallic "screener" layer remotely suppresses electron-phonon interactions in the current-carrying layer. This concept is most effective in 2D semiconductors whose scattering is dominated by screenable electron-phonon interactions, and in particular the Fröhlich coupling to polar-optical phonons. Such materials are common and characterised by overall low mobilities in the small doping limit, and much higher ones when the 2D material is doped enough for electron-phonon interactions to be screened by its own free carriers. We use GaSe as a prototype and place it in a heterostructure with doped graphene as the "screener" layer and BN as a separator. We develop an approach to determine the electrostatic response of any heterostructure by combining the responses of the individual layers computed within density-functional perturbation theory. Remote screening from graphene can suppress the long-wavelength Fröhlich interaction, leading to a consistently high mobility around $500$ to $600$ cm$^2$/Vs for carrier densities in GaSe from $10^{11}$ to $10^{13}$ cm$^{-2}$. Notably, the low-doping mobility is enhanced by a factor 2.5. This remote free-carrier screening is more efficient than more conventional manipulation of the dielectric environment, and it is most effective when the separator (BN) is thin.
