化学气相沉积石墨烯中的紧束缚太赫兹等离子体激元
Tight-binding terahertz plasmons in chemical vapor deposited graphene
摘要：
包括石墨烯和亚波长金属光栅的晶体管结构对于等离子体激元增强的太赫兹检测具有很大的希望。尽管有相当多的理论研究，但到目前为止，在这种结构中几乎没有发现太赫兹等离子体激元的实验证据。在这里，我们报告了在石墨烯绝缘体光栅结构中使用傅里叶变换光谱在5-10太赫兹范围内的等离子体激元的实验研究。即使在具有低载流子迁移率$\sim 10^3$ cm $^2$ /（Vs）的化学气相沉积（CVD）石墨烯中，等离子体共振在Drude吸收背景之上也是清晰可见的。我们认为，等离子体激元寿命是弱敏感的散射晶界和宏观缺陷，限制了CVD样品的流动性。在将光栅放置在石墨烯附近时，等离子体激元场变得紧密地束缚在金属条下方，而谐振频率由条宽度而不是光栅周期确定。我们的研究结果打开了大面积商用石墨烯共振太赫兹探测器的前景。
英文摘要：
Transistor structures comprising graphene and sub-wavelength metal gratings hold a great promise for plasmon-enhanced terahertz detection. Despite considerable theoretical effort, little experimental evidence for terahertz plasmons in such structures was found so far. Here, we report an experimental study of plasmons in graphene-insulator-grating structures using Fourier transform spectroscopy in 5-10 THz range. The plasmon resonance is clearly visible above the Drude absorption background even in chemical vapor deposited (CVD) graphene with low carrier mobility $\sim 10^3$ cm$^2$/(V s). We argue that plasmon lifetime is weakly sensistive to scattering by grain boundaries and macoscopic defects which limits the mobility of CVD samples. Upon placing the grating in close proximity to graphene, the plasmon field becomes tightly bound below the metal stripes, while the resonant frequency is determined by the stripe width but not by grating period. Our results open the prospects of large-area commercially available graphene for resonant terahertz detectors.
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