Design and performance considerations for perforated semiconductor thermal-neutron detectors

Perforated silicon structures backfilled with either B 10 or LiF 6 are presently under construction as high efficiency thermal-neutron detectors. Although many perforated structures are possible, there are three fundamental designs that are studied in the present work, namely (a) cylindrical perforations where holes are filled with neutron reactive material, (b) pillar configurations where semiconductor pillars are surrounded by neutron reactive material, and (c) trench structures where the trenches are filled with neutron reactive material. From results of Monte Carlo simulations, it is found that the trench structure affords the best efficiencies, exceeding 20% using conservative geometries, and over 35% for more aggressive structures. Simulated spectroscopic features and manufacturing constraints are presented and discussed.