Design and Modeling of Semiconductor Terahertz and Infrared Sensing Structures for Protein Characterization

The subject area of biological sensing becomes progressively more attractive for medicine and fundamental biological research. In these fields, the investigation of characteristic fingerprints of membrane proteins is important, as they are responsible for the communication and activity of biological cells. Moreover, these complex structures are essential for the transport of various substances into the cell and are suitable as a drug target. These kinds of proteins provide vibrational resonances between 200GHz and 2 THz. In this work, the design of coupled plasmonic antenna structures for the THzregime utilizing 3D-full-wave simulations are shown. These antennas consist of highly doped germanium on a silicon substrate and have a target frequency of 500 GHz. They provide high sensitivity for thin films in liquid water and suitable for protein characterization in the THz-regime. As the design with 3Dfull-wave simulations involves a significant computational effort, an alternative for the design of such antennas is shown. Plasmonic antennas are described with lumped circuit elements, which enables first designs with analytical calculations. Due to the description with lumped circuit elements, an approach for impedance matching for such antennas is given, and the structure is further optimized. After the THz-regime, the infrared regime is examined. In this regime, protein binding processes are observable. In this work, a novel structure consisting of silicon micropillar arrays is investigated to estimate the refractive index dispersion of proteins. These pillars provide high sensitivity for sub-monolayer films. The main results of this work provide suitable sensor structures for THz- and infrared protein characterization with high sensitivity. Furthermore, they are compatible with the standard BiCMOS process, which enables low-cost production for lab-on-chip architectures.