Superconducting characteristics of a MgB2 neutron detector fabricated on SiN membrane

We report a fabrication process for membrane-structured superconducting MgB2 neutron detectors and measurement of superconducting DC-characteristics. We prepared a MgB2 thin film on a SiN-film-coated Si substrate using multiple-target sputtering system. The 200-nm-thick MgB2 thin film was processed to create meandering lines by e-beam lithography technique, where the line width was 3 μm and the total length reached 6.3 mm. After the front side of the device had been fabricated, the back side of the device was etched with anisotropic Si etching using ethylene diamine pyrocatechol and etching apparatus to increase the sensitivity of the device. The membrane-structured MgB2 device showed good performance of the transition to superconductivity, namely, a TC,onset of 26.24 K, a TC,offset of 26.02 K, ΔTc of 0.22 K, and an RRR of 1.15.