High efficiency dual-integrated stacked microstructured solid-state neutron detectors (original) (raw)
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Applied Radiation and Isotopes, 2012
Silicon diodes with large aspect ratio 3D microstructures backfilled with 6 LiF show a significant increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology using detector stacking methods and summed-detector 6 Â 6-element arraying methods to dramatically increase the sensitivity to thermal neutrons. The intrinsic detection efficiency of the 6 Â 6 array for normal-incident 0.0253 eV neutrons was found 6.8% compared against a calibrated 3 He proportional counter.
Enhanced variant designs and characteristics of the microstructured solid-state neutron detector
2011
He replacement technology Microstructured diode Silicon wet-etching Charge transport simulation a b s t r a c t Silicon diodes with large aspect ratio perforated microstructures backfilled with 6 LiF show a dramatic increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology with increased microstructure depths and detector stacking methods to increase thermal neutron detection efficiency. The highest efficiency devices thus far have delivered over 37% intrinsic thermal neutron detection efficiency by devicecoupling stacking methods. The detectors operate as conformally diffused pn junction diodes with 1 cm 2 square-area. Two individual devices were mounted back-to-back with counting electronics coupling the detectors together into a single dual-detector device. The solid-state silicon device operated at 3 V and utilized simple signal amplification and counting electronic components. The intrinsic detection efficiency for normal-incident 0.0253 eV neutrons was found by calibrating against a 3 He proportional counter and a 6 LiF thin-film planar semiconductor device. This work is a part of ongoing research to develop solid-state semiconductor neutron detectors with high detection efficiencies and uniform angular responses.
IEEE Transactions on Nuclear Science, 2000
Silicon diodes with large aspect ratio trenched microstructures, back lled with LiF, show a dramatic increase in thermal neutron detection ef ciency beyond that of conventional thin-lm coated planar devices. Described in this work are advancements in the technology using detector stacking methods to increase thermal neutron detection ef ciency, along with the current process to back ll LiF into the silicon microstructures. The highest detection ef ciency realized thus far is over 42% intrinsic thermal neutron detection ef ciency by device-stacking methods. The detectors operate as conformally diffused pn junction diodes each having 1 cm area. Two individual devices were mounted back-to-back with counting electronics coupling the detectors together into a single dual-detector device. The solid-state silicon device was operated at 3 V and utilized simple signal ampli cation and counting electronic components that have been adjusted from previous work for slow charge integration time. The intrinsic detection ef ciency for normal-incident 0.0253 eV neutrons was found by calibrating against a He proportional counter.
Arrayed high efficiency dual-integrated microstructured semiconductor neutron detectors
2011 IEEE Nuclear Science Symposium Conference Record, 2011
Low-power microstructured semiconductor neutron detector (MSND) devices have lon g been investi g ated as a hi g h-efficiency replacement for thin-film diodes for thermal neutron detection. The detector devices were improved by stackin g two tcm 2 devices and inte g ratin g their responses to g ether to act as a sin g le diode, increasin g detection efficiency to over 42%. The need for lar g er active area devices has driven further improvement of the technolo g y. A lar g e active area device has been developed by arrayin g seventy-two tcm 2 devices to g ether into two 6x6 confi g urations, dual-stackin g them, and
Variant Designs and Characteristics of Improved Microstructured Solid-State Neutron Detectors
IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium
Perforated semiconductor neutron detectors are compact, high-efficiency, diode detectors that operate at low power. Microstructured neutron detector fabrication methods have been improved over previous manufacturing methods. The neutron detectors are easily fabricated from high purity n-type Si, in which patterned trenches are etched into the Si substrate, wherein shallow p-type junctions are diffused. The trenches are then backfilled with 6LiF powder, making the devices sensitive to reaction products from the 6Li(n,t)3He reaction. Pulse height spectra show improved signal-to-noise ratio, higher neutron counting efficiency, and excellent gamma-ray discrimination over previous microstructured neutron detector designs. Thermal neutron detection measurements from a 0.0253 eV diffracted neutron beam, yielded 20.4% intrinsic detection efficiency for devices with 245 micron deep trenches and 21% intrinsic detection efficiency for two back-to-back devices each having 113 micron deep trenches.
Applied Physics Letters, 2013
We report the continuous p-n junction formation in honeycomb structured Si diode by in situ boron deposition and diffusion process using low pressure chemical vapor deposition for solid-state thermal neutron detection applications. Optimized diffusion temperature of 800 °C was obtained by current density-voltage characteristics for fabricated p+-n diodes. A very low leakage current density of ∼2 × 10−8 A/cm2 at −1 V was measured for enriched boron filled honeycomb structured neutron detector with a continuous p+-n junction. The neutron detection efficiency for a Maxwellian spectrum incident on the face of the detector was measured under zero bias voltage to be ∼26%. These results are very encouraging for fabrication of large area solid-state neutron detector that could be a viable alternative to 3He tube based technology.
Characteristics of 3D Micro-Structured Semiconductor High Efficiency Neutron Detectors
IEEE Transactions on Nuclear Science, 2000
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 m 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.
Micro-structured high-efficiency semiconductor neutron detectors
2008
Perforated semiconductor diode detectors have been under development for several years at Kansas State University for a variety of neutron detection applications. The detectors are fabricated from high purity n-type Si. Sinusoidal trenches are etched into the substrate, into which shallow p-type junctions are diffused. The trenches are then backfilled with 6LiF powder to make the device sensitive to neutrons.
Present status of microstructured semiconductor neutron detectors
Journal of Crystal Growth, 2013
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 10-fold 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 V.
Low-cost fabrication of high efficiency solid-state neutron detectors
Proceedings of SPIE, 2016
The development of high-efficiency solid state thermal neutron detectors at low cost is critical for a wide range of civilian and defense applications. The use of present neutron detector system for personal radiation detection is limited by the cost, size, weight and power requirements. Chip scale solid state neutron detectors based on silicon technology would provide significant benefits in terms of cost, volume, and allow for wafer level integration with charge preamplifiers and readout electronics. In this paper, anisotropic wet etching of (110) silicon wafers was used to replace deep reactive ion etching (DRIE) to produce microstructured neutron detectors with lower cost and compatibility with mass production. Deep trenches were etched by 30 wt% KOH at 85°C with a highest etch ratio of (110) to (111). A trench-microstructure thermal neutron detector described by the aforementioned processes was fabricated and characterized. The detector-which has a continuous p +-n junction diode-was filled with enriched boron (99% of 10 B) as a neutron converter material. The device showed a leakage current of ~ 6.7 × 10-6 A/cm 2 at-1V and thermal neutron detection efficiency of ~16.3%. The detector uses custom built charge pre-amplifier, a shaping amplifier, and an analogto-digital converter (ADC) for data acquisition.