太赫兹时域光谱系统的单片集成技术研究

The terahertz free-space time domain spectroscopy is the major tool of the terahertz spectroscopy. But it has the drawback which cannot efficiently measure the liquid or infinitesimal traces of samples, because that the terahertz light sports in free space is large and water molecules absorb THz strongly. So we particularly present an approach of monolithic integration method based on evanescent-field THz time-domain spectroscopy. The fabrication and positioning of isolated regins of photoconductive LT-GaAs thin film will be developed to allow generation and detection of THz signals. The generated signals will propagate in-plane with a microstrip transmission line device. Polymer bonding and coplanar strip lines transmission are firstly proposed in this project, and we will obtain the best structrues of copuling electrodes and transmission lines, complete the intertation of single chip THz-TDS and realize the measurements of the two kinds of samples. This project makes a great breakthrough on the key techniques, including LT-GaAs epitaxial layer stripping and bonding. Its better progresses will enlarge the application of terahertz spectrum, and lay found ation for on-chip THz-TDS.

太赫兹时域光谱系统（THz-TDS）是太赫兹光谱学的主要研究平台，但传统系统不仅体积庞大，而且由于空间太赫兹光斑太大和水分子对太赫兹波的强烈吸收等问题，限制了系统在微量样品和液态样品的应用。因而，本项目将研究太赫兹时域光谱系统的单片集成技术，将太赫兹波的产生及探测、太赫兹波传输线以及样品区集成到同一基底上，利用太赫兹波微带线附近的消逝场与样品的相互作用，实现对微量或液态样品的光谱测量。该项目创新性地提出了采用聚合物键合、共面带状线传输的方法，将突破低温砷化镓外延层剥离、转移及键合等关键技术，获取耦合电极、传输线的最佳结构，完成太赫兹时域光谱系统的单片集成，实现对微量样品和液态样品的测试。该项目的顺利开展将拓展太赫兹光谱学的应用领域，并为太赫兹时域光谱系统的芯片化奠定基础。

为了突破太赫兹时域光谱系统的局限性，设计了一种将太赫兹泵浦区、探测区和传输波导集成到一个硅片上的太赫兹片上系统。该系统不仅能够解决上述系统的局限性，还能够省去样品测量前的光路准直环节，使样品的测量过程更加简便，同时集成化的系统也很大程度上提高了太赫兹波传输的稳定性。提出在砷化镓衬底上生长砷化铝，而后直接生长低温砷化镓的外延片结构。砷化铝作为低温砷化镓单层薄膜获取过程中的牺牲层，首次研究出高质量高效的薄膜获取条件，即在73℃下12.16%的盐酸溶液中进行砷化铝牺牲层的腐蚀。相比于已有工艺，单层的低温砷化镓薄膜更能够提高光电导天线产生的太赫兹波进入金属波导的耦合效率。且2μm厚的低温砷化镓薄膜能够直接贴合于目标衬底上，键合过程更加方便。另外，利用低温砷化镓薄膜制备了光电导天线，测试了其输出带宽。然后，设计并制作了微带线，测试了其性能，得到了太赫兹时域谱和频域谱，达到了项目的要求。