Demonstration of <i>β</i>-Ga₂O₃-Based Thermal Neutron Detector

Compact, accurate, and durable thermal neutron detectors utilizing ultra-wide bandgap semiconductors, such as gallium oxide (Ga2O<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{3}}\text {)}$ </tex-math></inline-formula> and diamond, hold great promise for the safe and long-term near-core monitoring of nuclear reactors in harsh environments. However, achieving low device leakage and efficient neutron detection remains a significant challenge. In this work, we demonstrate the first thermal neutron detector based on a large-area (9 mm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}}\text {)}$ </tex-math></inline-formula> p-NiO/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3 heterojunction diode. The device benefits from a low interfacial trap density, as demonstrated by the slight capacitance-frequency dispersion and low 1/f noise-equivalent power, resulting in an ultralow leakage current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-{8}}$ </tex-math></inline-formula> A (at −200 V). Consequently, it exhibits efficient charge collection efficiency for alpha particles (5.486 MeV) with an energy resolution of 10%. By integrating 10B film for neutron conversion, we achieved an intrinsic neutron detection efficiency of 0.82%, which approaches the predicted value from the Monte Carlo method, corresponding to 2.22% for thermal neutrons. These findings underscore the potential of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3 for applications in advanced radiation monitoring.