Photocurrent From Single Collision 14-MeV Neutrons in GaN and GaAs

• Published in: IEEE transactions on nuclear science Vol. 67; no. 1; pp. 221 - 227
• Main Authors: Jasica, Matthew J., Wampler, William R., Vizkelethy, Gyorgy, Hehr, Brian D., Bielejec, Edward S.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arsenides; Cascades; Energy dissipation; Energy loss; Gallium; Gallium arsenide; Gallium nitride; Gallium nitrides; IEL; Laboratories; Neutrons; NUCLEAR PHYSICS AND RADIATION PHYSICS; Nuclear reactions; Photoconductivity; photocurrent; Photoelectric effect; Photoelectric emission; radiation effects; Recoil; Silicon; Spectra
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2019.2949720

Accurate predictions of device performance in 14-MeV neutron environments rely upon understanding the recoil cascades that may be produced. Recoils from 14-MeV neutrons impinging on both gallium nitride (GaN) and gallium arsenide (GaAs) devices were modeled and compared to the recoil spectra of devices exposed to 14-MeV neutrons. Recoil spectra were generated using nuclear reaction modeling programs and converted into an ionizing energy loss (IEL) spectrum. We measured the recoil IEL spectra by capturing the photocurrent pulses produced by single neutron interactions with the device. Good agreement, with a factor of two, was found between the model and the experiment under strongly depleted conditions. However, this range of agreement between the model and the experiment decreased significantly when the bias was removed, indicating partial energy deposition due to cascades that escape the active volume of the device not captured by the model. Consistent event rates across multiple detectors confirm the reliability of our neutron recoil detection method.