SUMMARY

The core operating principle behind the detection of ionizing radiation is the generation and collection of charge carriers or photons in a bulk medium. The requirements of acceptable detection efficiency and complete energy deposition have imposed volume restrictions on these bulk mediums and hindered the application of nanostructured materials in radiation detection. This work investigates the use of vertically aligned carbon nanotubes (CNTs) as a sensing volume for ionizing radiation. Specifically, CNTs are integrated into a global gate field effect transistor geometry where the gate voltage controls the conductance of the device by modulating the Schottky barrier between the CNT channel and the source and drain electrodes. The current CNT-based radiation detector operates similarly to p-channel MOSFET where the device conductance increases at positive gate voltages. In the presence of diagnostic range x-rays, the current flowing through the device increases from the baseline noticeably due to the generated electron-hole pairs adding to the electric field felt by the CNT/electrode interface. In preliminary experiments, the CNT-based detector is sensitive to different x-ray energies and an appreciable gate voltage shift was measured. This novel device demonstrates the promise of integrating nanostructured materials into traditional semiconductor substrates for radiation detection. Furthermore, supplementary CNT properties are being explored to further increase the potential of the CNT-based detector.