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.
