Sensing the Interactions of Ionizing Radiation within a Silicon Substrate using Carbon Nanotubes
Arith Rajapakse
Abstract: Carbon nanotubes (CNTs) are well suited for sensing applications due to their electronic properties. In this work, a novel radiation detector was designed and fabricated around the concept of a field effect transistor (FET) like device where vertically aligned CNTs act as a sensor to the charge carriers generated by ionizing radiation in the semiconductor substrate. The electric field produced by the charge carriers alters the Schottky barrier between the CNTs and the source and drain electrodes and therefore, the overall device conductance. When exposed to radiation such as diagnostic x-rays, the baseline source-drain current flowing through the device quickly increases in response to the charge generated in the oxide and semiconductor substrate. The CNT-based detector is sensitive to various x-ray energies and fluences and an appreciable gate voltage can be measured. This device demonstrates the promise of integrating nanomaterials into traditional radiation detection mediums.