基于石墨烯的可调谐太赫兹探测器

Traditional terahertz detectors cannot have room temperature operation, fast response, high responsivity, low noise equivalent power, etc., especially without frequency resolution simultaneously, which greatly limits the rapid development of terahertz technology. Graphene has an ultra-high carrier mobility of up to 200,000 cm2/vs, and its plasmon resonance frequency is just in the terahertz band, which is very suitable as a field effect tunable terahertz detector. However, resonance detection of graphene terahertz detectors is still required at low temperature, which limits the application of graphene terahertz detectors. This project intends to prepare a short-channel graphene terahertz detector, so that the channel length is shorter than the propagation distance of the plasma wave, and the plasma wave resonance detection at room temperature will be realized. The mechanisms of generation, propagation, resonance and damping of plasma waves in graphene at different terahertz frequencies and gate voltage will be studied. The response and bandwidth characteristics of the detector will be further studied. At the same time, the effect of device configuration on the performance of graphene terahertz detectors will also be studied. The information of spectrum shifting will be analyzed, and a graphene tunable terahertz detector with frequency resolution will be finally developed, which is expected to lay a foundation for the future graphene terahertz spectrometer.

传统太赫兹探测器无法同时具备室温工作、响应速度快、响应度高、噪声等效功率低等特点，尤其是不具有频率分辨能力，很大程度上限制了太赫兹技术的快速发展。石墨烯具有高达200000cm2/vs的超高载流子迁移率，其等离子体共振频率正好处于太赫兹波段，非常适合作为场效应可调谐太赫兹探测器。然而，目前仍需在低温下才能实现石墨烯太赫兹探测器的共振探测，这使得石墨烯太赫兹探测器的应用受到极大限制。本项目拟制备短沟道石墨烯太赫兹探测器，使得沟道长度短于等离子体波的传播距离，实现室温下的等离子体波共振探测，并研究栅压调控及不同太赫兹频率下石墨烯中等离子体波的产生、传播、共振及阻尼机制，进一步提升器探测器的响应度及带宽特性，同时研究器件构型对石墨烯太赫兹探测器性能的影响，解析频谱移动的信息，最终开发出具有频率分辨能力的石墨烯可调谐太赫兹探测器，为以后的石墨烯太赫兹光谱仪奠定基础。

石墨烯是制备宽光谱超快光电探测器的最佳候选材料之一。石墨烯具有高达200000cm2/vs的超高载流子迁移率，其等离子体共振频率正好处于太赫兹波段，非常适合作为场效应可调谐太赫兹探测器。然而，目前仍需在低温下才能实现石墨烯太赫兹探测器的共振探测，这使得石墨烯太赫兹探测器的应用受到极大限制。.本项目中，我们采用有限时域差分法对太赫兹探测器的天线尺寸及结构进行仿真，得到高效耦合天线，并模拟得到石墨烯沟道内载流子的动态分布，理论研究石墨烯太赫兹探测器的光电性能。接下来，基于前期在理论分析中所发现的石墨烯超材料对太赫兹偏振特性的选择性响应特点，我们利用石墨烯的费米能级可调特性，设计了基于石墨烯超材料的太赫兹偏振探测、调控器件。在上述理论分析基础上，我们试制了太赫兹探测材料、器件。我们最初采用机械剥离和液相剥离两种方式制备了石墨烯。为进一步提高石墨烯的迁移率，我们又尝试了六方氮化硼/石墨烯/六方氮化硼的三层复合结构，显著提高了石墨烯的迁移率。此外，我们还探索了基于PDMS衬底的二维材料光电探测器制备工艺和基于硒化铟的太赫兹光电探测器。最后，在太赫兹波段，尝试采用连续域中束缚态（BIC）这新颖的光学机制提高光场调控能力和光与物质相互作用能力。我们着重研究了外加电场对BIC模式在动量空间移动的影响，以及外加电场对具有正负相反拓扑荷数的两个BIC融合过程的影响。本项目的研究成果既推进了基于石墨烯的太赫兹光电探测器研究，同时开拓了新型的基于无悬键PDMS衬底的太赫兹探测器和基于硒化铟的太赫兹探测器两种新的研究思路，为进一步推广本项目打下坚实基础。