Present status of microstructured semiconductor neutron detectors

Abstract

Semiconductor diode detectors coated with neutron reactive materials have been investigated as neutron detectors for many decades, and are fashioned mostly as planar diodes coated with boron-10 ( 10 B), lithium-6 fluoride ( 6 LiF) or gadolinium (Gd). Although effective, these detectors are limited in efficiency (the case for boron and LiF coatings) or in the ability to distinguish background radiations from neutron-induced interactions (the case for Gd coatings). Over the past decade, a renewed effort has been made to improve diode designs to achieve up to a tenfold increase in neutron detection efficiency over the simple planar diode designs. These new semiconductor neutron detectors are fashioned with a matrix of microstructured patterns etched deeply into the substrate and, subsequently, backfilled with neutron reactive materials. Intrinsic thermal-neutron detection efficiencies exceeding 40% have been achieved with devices no thicker than 1 mm while operating on less than 5 volts.

High-efficiency microstructured semiconductor neutron detectors for direct 3He replacement

“…The wafer was backfilled with nano-sized 6 LiF using centrifugal material deposition [12]. 6 LiF was produced by titration of 6 LiOH with HF.…”

“…Semiconductor with a thin-film coating of neutron reactive material deposited on a planar rectifying diode have been investigated for the past few decades as a potential neutron detector technology while maintaining high gamma-ray rejection characteristics [1][2][3]. MSNDs were developed as a means of increasing the relatively low efficiency of the planar thin-film-coated devices (typicallyo4-5% intrinsic) up to their theoretical maximums above 40% intrinsic detection efficiency for single 0.5-mm thick devices [4][5][6][7][8][9][10][11][12][13][14][15][16] while maintaining gamma-ray rejection ratios (GRR) of 10 À 6 or better [12]. The increase in intrinsic neutron detection efficiency stems from the two primary benefits of perforating a semiconductor diode; increased neutron absorption and increased probability of interaction of the charged neutron reaction products in the semiconductor diode.…”

Neutron detection using boron gallium nitride semiconductor material

“…The neutron detector using semiconductor material like boron carbide (BC) or microstructured Si substrate was proposed and developed. [10][11][12] Such neutron detection devices require a high-quality pn diode property, the material selection of neutron capture cross section, and the selection of semiconductor material for low γ -ray detection sensitivity.…”

Progress in alternative neutron detection to address the helium-3 shortage

“…There are a few semiconductor detectors that have been demonstrated that utilize a neutron capture material as the detector or on the semiconductor surface (e.g., coated Si, GaAs, boron carbide) [29]. Research on this technology has generated small detectors.…”