Solid-state neutron detectors based on thickness scalable hexagonal boron nitride

TL;DR

This study demonstrates the fabrication and characterization of scalable solid-state neutron detectors using hexagonal boron nitride (hBN), showing efficiency close to theoretical limits and potential for higher performance with enriched isotopes.

Contribution

It introduces a scalable fabrication process for hBN-based neutron detectors with high efficiency, highlighting the potential for improved performance using enriched hBN.

Findings

Detector efficiency increases with hBN thickness.

Measured efficiencies closely match theoretical maximums.

Potential for 21.4% efficiency with enriched hBN.

Abstract

This paper reports on the device processing and characterization of hexagonal boron nitride (hBN) based solid-state thermal neutron detectors, where hBN thickness varied from 2.5 to 15 microns. These natural hBN epilayers (with 19.9% B-10) were grown by a low pressure chemical vapor deposition process. Complete dry processing was adopted for the fabrication of these metal-semiconductor-metal (MSM) configuration detectors. These detectors showed intrinsic thermal neutron detection efficiency values of 0.86%, 2.4%, 3.15%, and 4.71% for natural hBN thickness values of 2.5, 7.5, 10, and 15 microns, respectively. Measured efficiencies are very close (more than 92%) to the theoretical maximum efficiencies for corresponding hBN thickness values for these detectors. This clearly shows the hBN thickness scalability of these detectors. A 15-micron thick hBN based MSM detector is expected to yield an efficiency of 21.4%, if enriched hBN (with ~100% B-10) is used instead of natural hBN. These results demonstrate that the fabrication of hBN thickness scalable highly efficient thermal neutron detectors is possible.