论文标题
2D半导体的语音限制移动性：四极杆散射和自由载体筛选
Phonon-limited Mobility of 2D Semiconductors: Quadrupole Scattering and Free-carrier Screening
论文作者
论文摘要
二维（2D）半导体表现出了下一代电子和光电子的巨大潜力。这些应用的重要属性是声子限制的电荷载体迁移率。从第一原理计算迁移率的通用方法依赖于电子偶联（EPC）矩阵的插值。但是，它忽略了由声子生成的动力四极杆的散射，从而限制了其精度。在这里，我们提出了一种结合四极散射的第一原理方法，从而导致了更好的插值质量，从而使单层MOS2和INSE的典型迁移率更为准确。该方法还允许自然掺入自由载体的效果，从而使我们能够有效地计算筛选的EPC，从而使掺杂的半导体的迁移率。尤其是，我们发现INSE的电子迁移率对载体浓度比MOS2的电子迁移率更敏感，因为内部INSE中的长距离散射更强。随着电子浓度的增加，INSE迁移率可以达到固有值的〜4倍，然后由于较重的电子状态的参与而减小。我们的工作提供了准确有效的方法来计算固有和掺杂的2D材料中声子受限的迁移率，并提高对其传输机制的基本理解。
Two-dimensional (2D) semiconductors have demonstrated great potential for next-generation electronics and optoelectronics. An important property for these applications is the phonon-limited charge carrier mobility. The common approach to calculate the mobility from first principles relies on the interpolation of the electron-phonon coupling (EPC) matrix. However, it neglects the scattering by the dynamical quadrupoles generated by phonons, limiting its accuracy. Here we present a first-principles method to incorporate the quadrupole scattering, which results in a much better interpolation quality and thus a more accurate mobility as exemplified by monolayer MoS2 and InSe. This method also allows for a natural incorporation of the effects of the free carriers, enabling us to efficiently compute the screened EPC and thus the mobility for doped semiconductors. Particularly, we find that the electron mobility of InSe is more sensitive to the carrier concentration than that of MoS2 due to the stronger long-range scattering in intrinsic InSe. With increasing electron concentration, the InSe mobility can reach ~4 times of the intrinsic value, then decrease owing to the involvement of heavier electronic states. Our work provides accurate and efficient methods to calculate the phonon-limited mobility in the intrinsic and doped 2D materials, and improves the fundamental understanding of their transport mechanism.
