Boron-10 nanoparticles filled silicon trenches for thermal neutron detection Application.

This paper reports on the use of ¹⁰B nano/microparticles in order to fill microstructures of deep trenches fabricated in n-type Si (110) bulk wafers for the development of solid-state thermal neutron detectors. The high aspect-ratio trenches were fabricated in the wafer by wet etching, with a trench width of 3.5 to 6 µm and a maximum depth of 120 µm. Boron was diffused at a temperature of ~1000 °C in order to convert the entirety of the delicate Si microstructures into a p⁺-n junction diode. The deep trenches of the diode were completely filled with ¹⁰B nanoparticles using a simple room-temperature process involving the pumping and venting of a vacuum chamber containing the etched wafer with ¹⁰B nanoparticles atop. The simple filling process was reproduced consistently, and the best 2.5 x 2.5 mm² device demonstrated an intrinsic thermal neutron (E_n <0.5 eV) detection efficiency of 32.2 ± 1.5% under a self-biased condition. This result is promising as it demonstrates a complete, low-cost fabrication process for the development of efficient thermal neutron detectors. [ABSTRACT FROM AUTHOR]