Ion-beam-induced charge study of new 4H-SiC detectors for microdosimetry

Novel radiation detectors based on 4H-SiC, developed at IMB-CNM, CSIC, have been characterized by means of the ion beam induced charge (IBIC) technique. In this work, two 4H-SiC microdetector designs (planar and 3D), with a thickness of 3 μm and a diameter of 30 μm, were tested using 2.5 MeV ions. The energy spectral response indicates diffusion effects at 0 V in the planar detector, which are significantly minimized in the 3D detector thanks to its geometry obtained through a SiC mesa process. The 3D architecture confines the charge collection region and reduces charge contributions from outside of the sensitive volume. Such characteristics highlight the advantages of 3D structures for applications requiring well-defined sensitive volumes, such as microdosimetry. Additionally, the 4H-SiC devices exhibited up to a 26% decrease in charge collection efficiency and a 16% reduction in the frequency mean lineal energy ( ) after irradiation of 2.5 MeV alpha particles at a fluence of 1.55 x 10 11 alphas/cm 2 at 0 V, attributed to charge collection degradation due to radiation-induced lattice defects that introduce carrier trapping and recombination centers. Applying reverse bias partially restored the initial performance. Therefore, proper calibration becomes essential once the accumulated fluence leads to variations in both energy spectrum and beyond the acceptable deviation limits.