Fabrication of Pillar-structured thermal neutron detectors

Nikolić, Rebecca J.; Conway, A. M.; Reinhardt, C. E.; Graff, R. T.; Wang, Tzu Fang; Deo, N.; Cheung, Chin Li

doi:10.1109/nssmic.2007.4437299

Cited by 17 publications

(11 citation statements)

References 8 publications

(13 reference statements)

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“…In hBN neutron detectors, the neutron capture, charge collection, and electrical signal generation occur in the same hBN layer. This is in contrast to boron coated conversion devices, in which the thermal neutron absorption takes place in the boron conversion layer and the generation of electrons and holes occurs in the semiconductor layer [13][14][15]. Thus, hBN detectors are potentially capable of providing higher detection efficiencies for thermal neutrons than those of the boron coated semiconductor conversion devices.…”

Section: Introductionmentioning

confidence: 97%

Fabrication and characterization of solid-state thermal neutron detectors based on hexagonal boron nitride epilayers

Doan

Majety

Grenadier

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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Solid-state thermal neutron detectors with improved detection efficiencies are highly sought after for many applications. Hexagonal boron nitride (hBN) epilayers have been synthesized by metal organic chemical vapor deposition on sapphire substrates. Important material parameters including the mobility-lifetime (μτ) product and the thermal neutron absorption length (λ) have been measured. For hBN epilayers with a room temperature resistivity of 5.3 Â 10 10 Ω cm, the measured μτ product of electrons is 4.46 Â 10 À 8 cm 2 /V and of holes is 7.07 Â 10 À 9 cm 2 /V. The measured λ values are 277 μm and 77 μm for natural and 10 B enriched hBN epilayers, respectively. Metal-semiconductor-metal detectors incorporating 0.3 mm thick hBN epilayers were fabricated. The reaction product pulse-height spectra were measured under thermal neutron irradiation produced by a 252 Cf source moderated by high density polyethylene block. The measured pulse-height spectra revealed distinguishable peaks corresponding to the product energies of 10 B and neutron reaction with the 0.84 MeV 7 Li peak being the most prominent. The detectors exhibited negligible responses to gamma rays produced by 137 Cs decay. Our results indicate that hBN epilayers are highly promising for realizing highly sensitive solid-state thermal neutron detectors with expected advantages resulting from semiconductor technologies, including compact size, light weight, ability to integrate with other functional devices, and low cost.

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Section: Introductionmentioning

confidence: 97%

Fabrication and characterization of solid-state thermal neutron detectors based on hexagonal boron nitride epilayers

Doan

Majety

Grenadier

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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“…The detector under development is based on high aspect ratio P-I-N diodes filled with 10 B, the neutron conversion material [4][5][6][7][8][9]. Thermal neutrons have a low probability of interacting with conventional semiconductor materials.…”

Section: Introductionmentioning

confidence: 99%

“…The pillar pitch is defined lithographically to allow the highest possible interaction of the energetic ions with the semiconductor pillars. When the 3D pillar detector is scaled to 50 µm, high efficiency (> 50 %) and high neutron-togamma discrimination (> 10 5 ) is predicted [4][5][6][7][8]. In this work, the effects of intrinsic layer thickness, pillar height, substrate doping as well as incident gamma energy on gamma discrimination are investigated.…”

Section: Introductionmentioning

confidence: 99%

Gamma discrimination in pillar structured thermal neutron detectors

et al. 2012

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Solid-state thermal neutron detectors are desired to replace 3 He tube based technology for the detection of special nuclear materials.3 He tubes have some issues with stability, sensitivity to microphonics and very recently, a shortage of 3 He. There are numerous solid-state approaches being investigated that utilize various architectures and material combinations. By using the combination of high-aspect-ratio silicon PIN pillars, which are 2 µm wide with a 2 µm separation, arranged in a square matrix, and surrounded by 10 B, the neutron converter material, a high efficiency thermal neutron detector is possible. Besides intrinsic neutron detection efficiency, neutron to gamma discrimination is an important figure of merit for unambiguous signal identification. In this work, theoretical calculations and experimental measurements are conducted to determine the effect of structure design of pillar structured thermal neutron detectors including: intrinsic layer thickness, pillar height, substrate doping and incident gamma energy on neutron to gamma discrimination.

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“…Several different designs of solid-state thermal neutron detectors are currently being investigated [2][3][4][5][6]. Our design is based on a high-aspect-ratio Si PIN diode pillar arrays filled with 10 B, which we have coined the "Pillar Detector" [7][8][9][10][11][12][13][14][15][16]. Moving from a gas medium to a solid-state material can dramatically reduce the size of the device by increasing the density of the neutron-absorbing material, which is attractive for hand-held applications.…”

Section: Introductionmentioning

confidence: 99%

Si pillar structured thermal neutron detectors: fabrication challenges and performance expectations

et al. 2011

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Solid-state thermal neutron detectors are desired to replace 3 He tube tube-based technology for the detection of special nuclear materials. 3He tubes have some issues with stability, sensitivity to microphonics and very recently, a shortage of 3 He. There are numerous solid-state approaches being investigated that utilize various architectures and material combinations. Our approach is based on the combination of high-aspect-ratio silicon PIN pillars, which are 2 µm wide with a 2 µm separation, arranged in a square matrix, and surrounded by 10 B, the neutron converter material. To date, our highest efficiency is ~ 20 % for a pillar height of 26 µm. An efficiency of greater than 50 % is predicted for our device, while maintaining high gamma rejection and low power operation once adequate device scaling is carried out. Estimated required pillar height to meet this goal is ~ 50 µm. The fabrication challenges related to 10 B deposition and etching as well as planarization of the three-dimensional structure is discussed.

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Fabrication of Pillar-structured thermal neutron detectors

Cited by 17 publications

References 8 publications

Fabrication and characterization of solid-state thermal neutron detectors based on hexagonal boron nitride epilayers

Fabrication and characterization of solid-state thermal neutron detectors based on hexagonal boron nitride epilayers

Gamma discrimination in pillar structured thermal neutron detectors

Si pillar structured thermal neutron detectors: fabrication challenges and performance expectations

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