MoS2/MX2/MoS2 trilayer TMDC field effect transistor based potentiometric nanobiosensors

Abstract

The ability to detect biomolecules and chemicals accurately, effectively, and promptly in variety of environments including applications in homeland security, clinical diagnoses, environmental monitoring, food safety, etc. has always been an important issue. For each of these applications, it is highly desirable that a small, ultra-sensitive, versatile and robust sensor be created. During the last decade, enormous progress in the synthesis of 1-D nanostructured materials and nanoparticles has allowed the fabrication of nanometer-sized sensors. Such materials and devices, with large surface-to-volume ratios and Debye length comparable to their small size, have already displayed superior sensitivity for the detection of various chemical and biological species. Their extremely small-scale also enables the miniaturization of sensors (e.g., portable, handheld sensors) as well as their multiplexing functionality to achieve simultaneous detection of multiple target molecules in a given sample. In spite of huge existing research regarding the fabrication of nanoscale bio and chemical sensors, the understanding of their sensing mechanism has been limited. In this thesis, we develop a comprehensive theoretical framework to correlate the geometry and physical properties of nanoscale sensors to their sensing performance of target molecules. This framework provides guidance for approaches about the sensor design and optimization. This work focuses on detection scope of biomolecule both in wet and dry environment. Label free electrical detection of biomolecules like enzyme, cell, DNA etc. with state of the art device like the one Junctionless Double Gate MOSFET has been investigated with the help of an analytical model. The impact of neutral biomolecules on the electrical characteristics of n-type Junctionless Double Gate MOSFET has been analyzed under dry environment situation. Factors crucial to biosensor like biomolecule’s position and their percentage area coverage have been investigated to find optimum arrangement of biomolecule for maximum sensitivity. In addition, this work also offers a comprehensive study of performance of sensor as a function of device physical parameters to maximize detection capability.