Scalable large-area solid-state neutron detector with continuous p–n junction and extremely low leakage current

Abstract

We report on the fabrication and characterization of solid-state thermal neutron detectors with detection areas up to 16cm2 that require only a single preamplifier for data acquisition. These detectors consist of a honeycomb-like micro-structured Si diode with boron-10 filled deep holes. A continuous p–n junction formed over the entire surface of the microstructure helps to achieve a low leakage current density of ~6.1×10−9A/cm2 at −1V for a 2.5×2.5mm2 detector. This low leakage current results in low electronic noise, which enables the fabrication of large-area detectors. An intrinsic thermal neutron detection efficiency of up to 26% was measured for a 2.5×2.5mm2 detector module and up to 24% was measured for a 1cm2 detector module. These measurements were obtained under zero bias voltage using a moderated californium-252 source. The relative efficiency remains almost the same when scaling the detector area up to 8cm2 by connecting 1cm2 detector modules in series. However, it decreases to 0.89 and 0.82, respectively, for 12 and 16cm2. Nevertheless, these results demonstrate the promise of using boron filled micro-structured Si diodes as a cost effective alternative to the helium-3 based neutron detection technology and the potential of fabricating scalable large-area solid-state neutron detectors that are desirable for many applications.