Achieving High Efficiency Neutron Detection With a 4H-SiC p-i-n-Type Micro-Trench Structure

Due to its radiation hardness and thermal resistance properties, silicon carbide (SiC) is a good candidate for neutron detection in harsh environments. To address the issues of low detection efficiency in thin-film-coated planar neutron detectors and the space charge–limited current (SCLC) effect in semi-insulating 4H-SiC micro-trench neutron detectors, a 5 mm × 5 mm micro-trench neutron detector based on a PiN-type 4H-SiC epitaxial wafer has been fabricated. Using inductively coupled plasma (ICP) etching, deep trenches with a depth ＞ 43 μm and an aspect ratio ＞4 are etched on the SiC wafer. Nanoscale ⁶LiF powder, used as the neutron conversion material, is dissolved in alcohol and filled into the trenches using a liquid centrifugation method. By optimizing the rotation speed and concentration of ⁶LiF, the quality of powder filling has improved significantly. At a reverse bias voltage of 500 V, the detector’s leakage current remains lower than 3 nA. Experimental results show a maximum neutron detection efficiency of 6.98 ±0.07%, with no observed SCLC effect.