Atomically thin (two-dimensional, 2D) semiconductors have shown great potential as the fundamental building blocks for next-generation electronics. However, all the 2D semiconductors that have been experimentally made so far have room-temperature electron mobility lower than that of bulk silicon, which is not understood. Here, by using first-principles calculations and reformulating the transport equations to isolate and quantify contributions of different mobility-determining factors, we show that the universally low mobility of 2D semiconductors originates from the high “density of scatterings,” which is intrinsic to the 2D material with a parabolic electron band. The density of scatterings characterizes the density of phonons that can interact with the electrons and can be fully determined from the electron and phonon band structures without knowledge of electron-phonon coupling strength. Our work reveals the underlying physics limiting the electron mobility of 2D semiconductors and offers a descriptor to quickly assess the mobility.

中文翻译：

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为什么二维半导体通常具有低电子迁移率

原子薄的（二维，二维）半导体已经显示出巨大的潜力，可作为下一代电子产品的基本组成部分。但是，到目前为止，实验上制造的所有2D半导体的室温电子迁移率都低于体硅的室温电子迁移率，这是无法理解的。在这里，通过使用第一性原理计算并重新构造了输运方程，以隔离和量化不同迁移率决定因素的贡献，我们证明了二维半导体普遍普遍的低迁移率源自高“散射密度”，这是硅固有的。具有抛物线电子带的2D材料。散射的密度表征了可以与电子相互作用的声子的密度，并且可以完全由电子和声子的能带结构确定，而无需了解电子-声子的耦合强度。我们的工作揭示了限制2D半导体电子迁移率的基本物理原理，并提供了一个描述符来快速评估迁移率。