Advancements on dual-sided microstructured semiconductor neutron detectors (DSMSNDs)

Microstructured semiconductor neutron detectors (MSNDs) represent a low-cost, high-efficiency means of solid-state thermal neutron detection. Trenches are etched into a pn-junction diode and backfilled with nano-sized
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LiF neutron converting material. Neutrons absorbed within the conversion material produce charged particle reaction products that interact within the semiconductor substrate and generate electron-hole pairs. The electron-hole pairs are collected by the applied bias, generating an electronic pulse and indicating a neutron event. Presently, single-sided MSNDs performance is approaching the theoretical maximum detection efficiency, with devices nearing 35% intrinsic thermal neutron detection efficiency. Single-sided MSNDs are limited in their detection efficiency due to neutron streaming between the trenches; incident neutrons will pass through the semiconductor substrate without detection. Dual-side microstructured semiconductor neutron detectors (DSMSNDs) alleviate this issue with an additional set of trenches etched into the backside of the diode. Neutrons streaming through the first set of trenches can be absorbed in the second set of trenches. Careful design of DSMSNDs can allow for detection efficiencies exceeding 70% for a single 1-mm thick detector. DSMSNDs etched 20-μm wide, 350-μm deep trenches, and 10-μm wide fins have achieved an intrinsic thermal neutron detection efficiency of 53.54±0.61% for neutrons normally incident on the front face of the detector using p-type contacts on both the front- and back-side fins.