石墨烯中光激发电子通过与声、光和表面极性光学声子耦合的非弹性散射和冷却
Inelastic scattering and cooling of photoexcited electrons through coupling with acoustic, optic and surface polar optic phonons in graphene
摘要：
声学、光学和表面极性光学声子是三种重要的固有和非固有声子模式，随着温度的升高，它们在衬底上越来越多地填充石墨烯;其与光激发的热载流子在均分制度中的耦合为电子-声子弛豫提供了重要的途径。本文从理论上研究了三种声子模在单层石墨烯中电子散射和冷却现象中的相对重要性，包括它们与超碰撞驱动功率损耗的比较，并在玻尔兹曼输运理论中得到了电子-声子散射率和冷却功率与能量关系的解析公式.所得到的解析解不仅与以前报道的数值积分形式所得到的散射率和冷却功率的结果很接近，而且还使我们能够导出冷却时间和热导的封闭形式的公式。泡利阻塞的重要作用，防止过渡到充满的能量状态也已阐明在估计的散射率和冷却功率密度的所有三种模式。所得到的公式提供了一个更好的洞察热电子现象的动力学给出了明确的看法，影响调查中的运输量的不同变量的相互作用。该公式也可以是潜在的有用的性能优化的运输量的数值优化方法，因为一阶和二阶导数很容易从这些公式推导。
英文摘要：
The acoustic, optic, and surface polar optic phonons are the three important intrinsic and extrinsic phononic modes that increasingly populate graphene on a substrate with rising temperatures; the coupling of which with photoexcited hot carriers in the equipartition regime provides significant pathways for electron-phonon relaxation. In this paper, we theoretically investigate the relative significance of the three phononic modes in electron scattering and cooling phenomena in single layer graphene, including their comparison with supercollision driven power loss, and obtain analytical formulae on the energy dependence of electron-phonon scattering rate and cooling power in the Boltzmann transport formalism. The obtained analytical solutions not only closely reproduce the results for scattering rate and cooling power, as that obtained from the earlier reported numerically tractable integral forms, but also enable us to derive closed-form formulae of the cooling time and thermal conductance. The important role of Pauli blocking that prevents transition to filled energy states has also been elucidated in the estimation of the scattering rate and cooling power density for all the three modes. The obtained formulae provide a better insight into the dynamics of hot electron phenomena giving an explicit view on the interplay of the different variables that affect the transport quantities under investigation. The formulae can also be potentially useful for performance optimization of transport quantities in numerical optimization methods since the first and second-order derivatives are easily deducible from these formulae.
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