Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Electrical Engineering

Major Professor

Syed K. Islam

Committee Members

Jayne Wu, Gong Gu, Ramki Kalyanaraman


The history of biosensors began in 1962 with the invention of enzyme electrodes by Leland C. Clark. Since then, biosensors have come a long way with simultaneous contributions in various fields such as biology, chemistry, material science, electronics, physics and VLSI. With the advancement in science and technology, smaller, more sensitive and dependable biosensors have become a reality. Still the need for cost-effective, sophisticated, reliable, robust biosensors that can be used to detect multiple types of biomolecules remains a technological challenge to be resolved.

The proposed AlGaN/GaN High Electron Mobility Transistors (HEMTs) have excellent prospect to become the biosensor platform of the future, as is investigated in this work in contrast to other types of biosensors. These devices excel over their silicon counterparts because of their inherent properties such as chemically stable bulk and surface properties and the availability of high-density two-dimensional electron gas (2DEG) at the hetero-interface which allows a highly sensitive detection of the surface-charge related phenomena. Using a floating gate configuration, only the drain current changes pertinent to biomolecule immobilization are observed. The test results are correlated with an analytical model which provides insight into the device physics. The high mobility and sensitivity inherent in its material system as well as device structure, robustness due to wide bandgap and system-level advantages make it the ultimate choice as a biosensor platform.

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