标题： 金属与二维半导体之间的光电导效应 显示英文标题

标题： Photon drag at the junction between metal and 2d semiconductor

摘要： 光子拖曳是一种光电流生成机制，其中电磁（EM）场动量直接传递给载流子。 人们认为由于光子动量相对于载流子的典型动量较小，因此光子拖曳效应很小。 在这里，我们表明在金属和二维材料之间的结处，光子拖曳变得特别强，因为在衍射时会产生高度不均匀的局部电磁场。 为此，我们将金属-二维材料结处的精确衍射理论与光子拖曳的微观输运理论相结合，并推导出相应光电压对电磁场参数和二维系统参数的功能依赖关系。 电压响应性与电磁频率$\omega$、载荷的面密度以及仅取决于二维电导率（以光速为单位）$\eta = 2\pi \sigma/c$和光极化的无量纲动量转移系数$\alpha$成反比。 对于$p$极化的入射光，即使二维电导率$\eta$极小，动量转移系数仍然有限，这是动态避雷针效应的结果。 对于$s$极化的入射光，动量转移系数按$\eta \ln \eta^{-1}$的比例变化，这源于线性结的长程偶极辐射。 一个简单的估算表明，对于$p$极化，在结处的热电和光拖曳光伏电压的比值大致为$\omega\tau_\varepsilon$，其中$\tau_\varepsilon$是能量弛豫时间，而对于$s$极化，光拖曳总是超过热电效应。 显示英文摘要

摘要： Photon drag represents a mechanism of photocurrent generation wherein the electromagnetic (EM) field momentum is transferred directly to the charge carriers. It is believed to be small by the virtue of low photon momentum compared to the typical momenta of the charge carriers. Here, we show that photon drag becomes particularly strong at the junctions between metals and 2d materials, wherein highly non-uniform local EM fields are generated upon diffraction. To this end, we combine an exact theory of diffraction at 'metal-2d material' junctions with microscopic transport theory of photon drag, and derive the functional dependences of the respective photovoltage on the parameters of EM field and 2d system. The voltage responsivity appears inversely proportional to the electromagnetic frequency $\omega$, the sheet density of charge, and a dimensionless momentum transfer coefficient $\alpha$ which depends only on 2d conductivity in units of light speed $\eta = 2\pi \sigma/c$ and light polarization. For $p$-polarized incident light, the momentum transfer coefficient appears finite even for vanishingly small 2d conductivity $\eta$, which is a consequence of dynamic lightning rod effect. For $s$-polarized incident light, the momentum transfer coefficient scales as $\eta \ln \eta^{-1}$, which stems from long-range dipole radiation of a linear junction. A simple estimate shows that the ratio of thermoelectric and photon drag photovoltages at the junction for $p$-polarization is roughly $\omega\tau_\varepsilon$, where $\tau_\varepsilon$ is the energy relaxation time, while for $s$-polarization the photon drag always dominates over the thermoelectric effect.