Wide-Bandgap Microstructured Semiconductor Neutron Detector

There is a need for high-efficiency, radiation hard, high-temperature neutron detectors at nuclear reactor and nuclear physics facilities. Nuclear physic experiments require neutron detectors that are robust, compact, low-power, and have high-sensitivity, while stably operating in harsh environments, e.g., high-temperature and high radiation-dose. Wide-bandgap semiconductors will tolerate such environments. Furthermore, the devices must be insensitive to background radiation, while retaining high detection efficiency, preferably above 30%. The objective of this project is to design and build for the first time a high- efficiency thermal-neutron detector made from wide-bandgap semiconductors. The detector will be based on the microstructured semiconductor neutron detector technology. The final deliverable for this project is a WB-MSND that has at least a thermal-neutron detection efficiency of 20% at an operating temperature of >100C. A secondary deliverable is a packaged WB-MSND with readout electronics that can operate within high-temperature and high-dose environments. In phase one, WB-MSNDs fabrication methodology, specifically micromachining these hard semiconductor materials and diode-contact fabrication, raw-material supply-chain trade study, and WB- MSND packaging for wide-range temperature operation (coefficient of thermal expansion can cause packaging issues) will be investigated. In phase two, further work will be pursued to fully develop the WB-MSND sensor and reduce its production-cost point, design and develop the readout electronics for the WB-MSND, and develop the technology to be arrayed in 1-cm2 two dimensional arrays. The new technology will deliver compact, high-efficiency, radiation hard, thermal-neutron detectors capable of real-time neutron measurements; such compact, solid-state semiconductor devices currently do not exist. Commercial Applications and Other Benefits: The scientific and commercial impact from the proposed research is expected to be significant. The results from this project will directly impact the quality of materials research and nuclear physics research planned for many nuclear science sites, e.g., ORNL SNS, Michigan State’s FRIB. Wide-bandgap microstructured semiconductor neutron detector technology will dramatically improve the life of neutron detectors that are placed in high-fluence areas, e.g., detectors at CERN’s Large Hadron Collider (LHC) are subject to fluences >1015 fast hadrons/cm2. Although this research is oriented towards the nuclear physics applications, its successful completion will have profound effects in many areas of the scientific and industrial community. A wide-bandgap microstructured semiconductor neutron detector sensor/array has direct applications in many other areas of science and engineering, such as in high-resolution neutron radiography/tomography, in neutron diffraction studies for stress/strain measurements in materials with internal defects, and for surface diffraction studies of coatings and material fracturing,. The development of the novel detector designs proposed will benefit a wide spectrum of applications beyond the science of nuclear physics. Wide-band- gap semiconductors such as SiC, GaN, AlN, and maybe diamond, make these detector semiconductor materials attractive alternatives in applications in harsh environments by virtue of their lower operating voltage, faster charge-collection times compared with those of gas-filled detectors, and compact size.