Novel n-type Mg2B14 on silicon diode: Demonstration of a thermal solid state neutron detector

A solid state heterojunction diode based on a micrometer thick n-Mg2B14 on p-type Si substrates, deposited by laser ablation, was demonstrated as thermal neutron detector. The neutron signal from a thermal neutron source with 105 ns−1 cm−2 from a spallation beam and moderated Cf-252 source producing 5 thermal n/s was registered at reverse bias of 20 V and 10 μs shaping time, with the diode detector cooled to temperature ranging to liquid nitrogen boiling point to reduce thermally induced leakage currents. The results were consistent with simulated neutron capture efficiencies considering material imperfections. Simulations also showed detector performance and enhancement of the efficiency with increasing boride thickness and using enriched boron. For a 10 μm enriched in B-10 Mg2B14 detector, efficiencies in excess of 30% may be possible, with a high gamma–neutron discrimination level.

► Thermal neutron detector diode of n-type Mg2B14 on p-Si was demonstrated.
► Detector efficiency was compared to Monte Carlo simulations performed.
► Detector efficiency could be improved by boride layer optimization.
► The devices are fabricated on Si substrates, enabling low-cost applications.