Study highlights gallium oxide’s promise for next generation radiation detectors

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New research from North Carolina State University finds that radiation detectors making use of single-crystal gallium oxide allow for monitoring X-ray radiation in near-real time.

“We found that the gallium oxide radiation detector worked very fast, which could offer benefits to many applications such as medical imaging,” says Ge Yang, an assistant professor of nuclear engineering at NC State and corresponding author of a paper on the work. “This is particularly exciting because recent research tells us that gallium oxide has excellent radiation hardness – meaning it will keep doing its job even when exposed to high amounts of radiation.

“In short, we think this material is faster than many existing materials used in X-ray detection – and able to withstand higher levels of radiation.”

For this study, the researchers made a radiation detector that incorporated a single-crystal sample of gallium oxide with electrodes attached on either side. The researchers applied different bias voltages across the gallium oxide while exposing the material to X-ray radiation.

The researchers found that there was a linear increase in current passing out of the gallium oxide relative to the level of X-ray exposure. In other words, the higher the level of X-ray radiation exposure, the higher the increase in current from the gallium oxide.

“This linear relationship, coupled with the fast response time and radiation hardness, make this a very exciting material for use in radiation detector technologies,” Yang says. “These could be used in conjunction with medical imaging technologies, or in security applications like those found at airports.”

The paper, “Fast X-ray detectors based on bulk β-Ga2O3 (Fe),” is published in the Journal of Materials Science. First author of the paper is Ibrahim Hany, a Ph.D. student at NC State. The paper was co-authored by Ching-Chang Chung, a postdoctoral researcher at NC State.

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Note to Editors: The study abstract follows.

“Fast X-ray detectors based on bulk β-Ga2O3 (Fe)”

Authors: Ibrahim Hany, Ge Yang and Ching-Chang Chung, North Carolina State University

Published: April 22, Journal of Materials Science

DOI: 10.1007/s10853-020-04665-9

Abstract: (010) EFG-grown Fe-doped β-Ga2O3 was tested as a low-noise X-ray detector with Ti/Au electrodes vertical structure. Its performance at low, high and no applied voltages was examined. The fabricated detector showed high X-ray detection performance manifested in its signal’s short fall and rise time (< 0.3 s) in all operation modes, showing two orders of magnitude decrease in response time of β-Ga2O3 X-ray detectors. The same temporal response was exhibited by a tested Au/Ni/β-Ga2O3/Ti/Au device. The detector’s signal is also characterized by excellent linear relation with X-ray tube current and high signal-to-noise ratio (SNR) optimized at − 5 V (> 103). Moreover, the X-ray-induced current signal exhibits high stability. Sub-band UV photocurrent signal showed a significantly slower response compared to X-ray-induced conductivity signal. Possible charge transport mechanisms involving ion migration are suggested and discussed. In this study, Fe doping is shown to significantly improve X-ray detection performance of Ga2O3, consolidating the applicability of Ga2O3 as a next-generation X-ray detector functioning with low power, high SNR and linearity, and significantly improved transient characteristics.

This post was originally published in NC State News.