A SiC Microstructured Neutron Detector Based on Deep Trench Etching Process

Due to their radiation hardness and thermal resistance properties, silicon carbide (SiC) detectors have received much attention for neutron detection. To solve the problem of low detection efficiency in thin-film-coated planar neutron detectors, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 1$ </tex-math></inline-formula> cm microstructured neutron detector (MSND) based on 500-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m high-purity semi-insulating (HPSI) 4H-SiC is fabricated. By utilizing inductively coupled plasma (ICP) etching technique, deep trenches are etched on the SiC wafer, with a trench depth of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 51~\mu $ </tex-math></inline-formula>m and an aspect ratio <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ge 5$ </tex-math></inline-formula>. Nanoscale 6LiF powder, serving as the neutron conversion material, is dissolved in alcohol and filled into the trenches using a liquid centrifugation method. When the reverse bias voltage is up to −800 V, its dark current is lower than 6 nA. Experimental results show that the maximum value of the neutron detection efficiency is 3.28%. In the subsequent research, we will continue to optimize the deep etching process of SiC materials and the filling process of 6LiF powder, which should improve the detection efficiency further.