Date of Award




Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Nanoscale Science and Engineering


Nanoscale Engineering

Content Description

1 online resource (xii, 145 pages) : PDF file, illustrations (some color)

Dissertation/Thesis Chair

Nathaniel C Cady

Committee Members

Thomas Begley, Magnus Bergkvist, Serge Oktyabrsky, Jason Shepard


Immobilized nucleic acids, Field-effect transistors, Biosensors, Hafnium oxide

Subject Categories

Biomedical Engineering and Bioengineering | Nanoscience and Nanotechnology


The research presented herein exploits the terminal phosphate group on single stranded DNA molecules for direct immobilization to surfaces utilized in semiconductor device fabrication with the end goal of transistor based DNA sensors. As a demonstration of the feasibility of this immobilization strategy DNA immobilization to a variety of surfaces was evaluated for usefulness in biosensor applications. It was determined that DNA can be directly immobilized to a variety of semiconductor surfaces through the terminal phosphate group. Further, this immobilization allows for the hybridization of the immobilized DNA to complementary target in solution. The immobilization of DNA to hafnium dioxide was particularly of interest due to its use in modern nanoelectronics manufacturing. The interactions between DNA and various forms of hafnium dioxide were thoroughly studied in order to understand and optimize the immobilization of DNA to hafnium dioxide for field effect transistor (FET) based DNA sensors. A secondary immobilization route of DNA to a subset of hafnium dioxide surfaces was identified and we have shown that this mechanism is through the nitrogenous bases of the probe molecule. Finally, a novel FET sensor was designed and developed which incorporated III-V materials and hafnium dioxide. The development of the sensor was carried out with the long term goal of determining if FET DNA sensors would have increased sensitivity if fabricated with: 1) the direct immobilization of probe DNA; 2) hafnium dioxide gate dielectric; and/or 3) III-V FET structure. Here, we demonstrate a proof-of-concept device that incorporates these three features and is capable of detecting DNA in solution, DNA immobilized to the surface, and DNA hybridization events.