Fast and Sensitive Terahertz Detection Using an Antenna-Integrated Graphene pn Junction
Fast and Sensitive Terahertz Detection Using an Antenna-Integrated Graphene pn Junction
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DOI：
10.1021/acs.nanolett.8b04171
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发表时间：
2019-05-01
期刊：
影响因子：
10.8
通讯作者：
Koppen, Frank H. L.
中科院分区：
文献类型：
--
作者：
Castilla, Sebastian;Terres, Bernat;Koppen, Frank H. L.
虽然探测太赫兹（THz）频率的光对于大范围的应用很重要，但电流探测器在灵敏度、速度、工作温度和光谱范围方面通常有几个缺点。在这里，我们使用石墨烯作为光活性材料来克服所有这些限制。我们介绍了一种利用光热电（PTE）效应的新型太赫兹辐射探测器，该探测器基于双门控偶极天线的设计，其间隙类似于100 nm。这种窄间隙天线同时在位于天线上方的石墨烯通道中产生pn结，并将入射辐射强烈地集中在该pn结处，从而产生光响应。我们证明了这种新型探测器具有出色的灵敏度，室温下的噪声等效功率为80 pW/根Hz，响应时间低于30 ns（设置限制），高动态范围（线性功率依赖超过3个数量级）和宽带操作（测量范围1.8-4.2太赫兹，天线限制），这满足了目前最先进的探测器所缺少的组合。重要的是，基于实验、分析模型和数值模拟之间的一致性，我们已经对PTE效应如何引起太赫兹诱导光响应有了深入的了解，这对进一步优化探测器非常有价值。
Although the detection of light at terahertz (THz) frequencies is important for a large range of applications, current detectors typically have several disadvantages in terms of sensitivity, speed, operating temperature, and spectral range. Here, we use graphene as a photoactive material to overcome all of these limitations in one device. We introduce a novel detector for terahertz radiation that exploits the photothermoelectric (PTE) effect, based on a design that employs a dual-gated, dipolar antenna with a gap of similar to 100 nm. This narrow-gap antenna simultaneously creates a pn junction in a graphene channel located above the antenna and strongly concentrates the incoming radiation at this pn junction, where the photoresponse is created. We demonstrate that this novel detector has an excellent sensitivity, with a noise-equivalent power of 80 pW/root Hz at room temperature, a response time below 30 ns (setup-limited), a high dynamic range (linear power dependence over more than 3 orders of magnitude) and broadband operation (measured range 1.8-4.2 THz, antenna-limited), which fulfills a combination that is currently missing in the state-of-the-art detectors. Importantly, on the basis of the agreement we obtained between experiment, analytical model, and numerical simulations, we have reached a solid understanding of how the PTE effect gives rise to a THz-induced photoresponse, which is very valuable for further detector optimization.