Characteristics of 3D Micro-Structured Semiconductor High Efficiency Neutron Detectors

Silicon diodes with large aspect ratio perforated micro-structures backfilled with 6 LiF show a dramatic increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in the following are advancements in the technology with increased perforation depths. Perforated silicon diodes with three different etched micro-structure patterns were tested for neutron counting efficiency. The etched micro-structure patterns consisted of circular holes, straight trenches, and continuous sinusoidal waves, with each pattern etched 200 mum deep. Normal incident neutron counting efficiencies were determined to be 9.7%, 12.6%, and 16.2% for circular hole, straight trench, and sinusoidal devices, respectively, at a reverse bias of 3 volts. The perforated neutron detectors demonstrate limited sensitivity to high-energy photon irradiation with a 60 Co gamma-ray source. This work is part of on-going research to develop solid-state semiconductor neutron detectors with high detection efficiencies and uniform angular responses.