Characterisation of the Effects of Radiation Damage on Low Gain Avalanche Diodes for Low-LET Microdosimetry

Low gain avalanche diodes (LGADs) have possible applications in microdosimetry to improve the signal-to-noise ratio of low-LET radiation. The effects of radiation damage on a 1 × 1 mm² LGAD were characterised using an ion beam induced current (IBIC) technique on a scanning ion beam microprobe with proton energies of 1.8 MeV, 3.2 MeV and 5 MeV. There were difficulties in the implementation of the LGADs with radiation damage due to the high leakage current along with spurious noise. Due to the additional temporal and spatial information provided by the IBIC technique, the signal-to-noise ratio was improved by applying background subtraction along with spatial and temporal masking. It was found that the gain of the devices decreased with increasing radiation damage and linear energy transfer (LET). However, the resolution improved with increasing radiation damage and LET. As a result of the strong dependence of the gain on particle type, energy and radiation damage, more investigation or the development of alternative technologies is required to improve the applicability of LGADs to radiation microdosimetry.