Improved High Efficiency Stacked Microstructured Neutron Detectors Backfilled With Nanoparticle 6LiF

Silicon diodes with large aspect ratio trenched microstructures, backfilled with ⁶LiF, show a dramatic increase in thermal neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology using detector stacking methods to increase thermal neutron detection efficiency, along with the current process to backfill ⁶LiF into the silicon microstructures. The highest detection efficiency realized thus far is over 42% intrinsic thermal neutron detection efficiency by device-stacking methods. The detectors operate as conformally diffused pn junction diodes each having 1 cm² area. Two individual devices were mounted back-to-back with counting electronics coupling the detectors together into a single dual-detector device. The solid-state silicon device was operated at 3 V and utilized simple signal amplification and counting electronic components that have been adjusted from previous work for slow charge integration time. The intrinsic detection efficiency for normal-incident 0.0253 eV neutrons was found by calibrating against a ³He proportional counter.