Fast neutron detector based on surface-barrier VPE GaAs structures

Abstract

Surface-barrier structures based on thin high-purity GaAs epilayers with a polyethylene converter were studied as fast neutron detectors. A continuous Schottky barrier with a large area of 5 × 5 mm 2 to the high-purity GaAs epilayers was fabricated using a Pt/TiN/Au metallization system. Results of measurement of electric parameters and α-particle spectra are presented. The fast neutron spectra from the 241 Am-Be source measured by the recoil proton method for various thicknesses of the polyethylene converter and various operating biases are shown as well. The proposed detectors have shown high neutron detection efficiency of 1.30 • 10 −3 puls./neutr. and an acceptable signal-to-background ratio (at level of 50) as well as the capability to operate efficiently without any external bias.

Semi-insulating GaAs based detector of fast neutrons produced by D–T nuclear reaction

“…Our results are in agreement with those published by other authors. The authors in [3] obtained a neutron detection efficiency of 0.13% using an epitaxial GaAs detector with a polyethylene converter exposed to an 241 AmBe neutron source (4.08 MeV mean neutron energy). Another group [1] reached an intrinsic detection efficiency of 0.076% using an 241 AmBe source and 0.025% with 252 Cf (2.2 MeV mean neutron energy) utilizing a semiconductor alpha detector with a polyethylene conversion layer.…”

“…Semiconductor based detectors with a neutron conversion layer present a very promising solution of fast neutron detectors, exhibiting compactness, small dimensions and high spatial resolution. Conversion layers for fast neutrons are attached to the detector in contact planar geometry and are usually based on polyethylene (PE) [1][2][3] or high density polyethylene (HDPE) [4][5][6], but also on fast plastic scintillator [7].…”

Semi-insulating GaAs detectors with HDPE layer for detection of fast neutrons from D–T nuclear reaction

“…In Ref. 4, the authors obtained a neutron detection efficiency of 0.13 % using an epitaxial GaAs detector with a polyethylene converter exposed to an 17 We have obtained an experimental detection efficiency of 0.113 %, using the optimal thickness of HDPE layer (500 µm) for an 241 AmBe neutron source in our previous research described in Ref. 7.…”

“…Recent processing methods for silicon and gallium arsenide allow realization of moderate-to high-efficiency neutron detectors. 1 Conversion layers for fast neutrons are attached to the detector in contact planar geometry and are usually based on polyethylene (PE) 2,3,4 and high density polyethylene (HDPE), 5,6,7 but also on fast plastic scintillator. 8 We have optimized our bulk semi-insulating (SI) GaAs detectors for fast-neutron detection by a multi-pixel structure of a Schottky contact.…”

Characterization and simulation of fast neutron detectors based on surface-barrier VPE GaAs structures with polyethylene converter

“…Surface-barrier structures based on thin (less than or equal to 50 µm) high-purity VPE (Vapor-Phase Epitaxy) GaAs epilayers were proposed as a sensor for fast neutron detection by the recoil proton method [17]. This has allowed to reduce the detection threshold of recoil protons and improve the signal-to-gamma-background ratio owing to reducing the absorption of γ-rays in the active region of the detector as well as increase the operating temperature and radiation stability in comparison with silicon.…”