Texas Tech University Nanophotonics research team has achieved a major breakthrough in applying ultrawide bandgap (UWBG) semiconductors to nuclear fusion technology
Texas Tech University Nanophotonics research team has achieved a major breakthrough in applying ultrawide bandgap (UWBG) semiconductors to nuclear fusion technology, marking the first successful creation of a semiconductor detector for 14.1 MeV deuterium-tritium (D-T) fusion neutrons with a practical 5 percent detection efficiency.
The research was led by Hongxing Jiang, Horn Distinguished Professor, Edward E. Whitacre Jr. Chair in the Department of Electrical and Computer Engineering, and co-director of the Nanophotonics Center; Jingyu Lin, Horn Distinguished Professor, Linda F. Whitacre Chair in the Department of Electrical and Computer Engineering, and co-director of the Nanophotonics Center; and Jing Li, research professor. They were joined by doctoral students Gokul Somasundaram and Zaid Alemoush. The project was supported by the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) through its 2021 OPEN program.
Nuclear fusion offers the potential for a nearly limitless, clean energy source, but significant engineering challenges remain. One of the most critical hurdles is detecting and managing the 14.1 MeV neutrons generated during the fusion of deuterium and tritium, the two heavy isotopes of hydrogen most commonly used in fusion reactions.
“Robust and efficient neutron detectors are essential for monitoring and controlling the fusion process, mitigating the impact of neutron radiation on materials, and ensuring efficient breeding of tritium fuel,” Jiang said.
Detecting fast neutrons using compact semiconductor detectors is exceptionally difficult due to the low interaction cross-section of fast neutrons with matter. Currently, no semiconductor-based detectors with practical detection efficiency for 14.1 MeV neutrons exist.
The Texas Tech team overcame this challenge by engineering an effective neutron interaction path length of 1 centimeter. Using 1-millimeter thick, 4-inch diameter hexagonal boron nitride (h-BN) quasi-bulk crystals grown by Alemoush through hydride vapor phase epitaxy (HVPE), Somasundaram fabricated a stacked detector in a lateral geometry with a total thickness of 5 millimeters and length of 1 centimeter.
The resulting detector achieved a neutron detection efficiency of 5 percent and a charge collection efficiency of 59 percent when exposed to a 14.1 MeV neutron beam aligned parallel to the c-plane of h-BN. The device also exhibited a significant neutron-generated direct current, suggesting the potential for portable and battery-powered D-T fusion neutron sensors.
The achievement builds on the team’s earlier work developing h-BN thermal neutron detectors with a record-high detection efficiency of 60 percent, published in Applied Physics Letters and Journal of Applied Physics.
According to Jiang, the team’s results demonstrate the feasibility of creating highly sensitive, compact, radiation-hard, and battery-powered D-T fusion neutron sensors. Such devices could have wide-ranging applications, including advanced nuclear reactor design, fusion energy development, and nuclear waste management.
The researchers also anticipate that h-BN semiconductor detectors capable of simultaneously detecting both thermal and fast neutrons could open new possibilities in neutron detection technologies not achievable with existing materials.
Looking ahead, the team plans to refine the crystalline quality of h-BN quasi-bulk crystals and optimize detector geometry to further enhance efficiency and sensitivity. They are also seeking collaboration with partners specializing in system integration to test these detectors in real D-T fusion environments.
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