Abstract: The charge collection characteristics and energy deposition characteristics of SOI-Si microdosimeter were studied by using TCAD and Monte Carlo method. The variation of electric field distribution with the shape and size of detection unit, electrode injection depth, incident particle type and energy was analyzed. And the variation of the micro dose spectrum with the shape and size of the detection unit and the thickness of the PMMA conversion layer was also analyzed. The simulation results showed that in the range of 10 μm, the cylindrical or cubic structure of the silicon detection unit had little influence on the charge collection efficiency and energy deposition. The higher the detection unit height and the smaller the radius, the higher the charge collection efficiency. The thickness of PMMA conversion layer had a certain influence on the microdose spectrum. With the increase of PMMA thickness, the proportion of secondary particles generated by neutron and γ-ray that were stopped in the silicon sensitive region will increase, which leads to the increase of the peak value of the microdose spectrum.

Key words: SOI-Si microdosimeter, charge collection, energy deposition, microdose spectrum