Comparing different bulk radiation damage models in TCAD simulations of small-pitch 3D Si sensors

Small-pitch, thin 3D Si sensors have been developed for the ATLAS and CMS experiment upgrades at the High Luminosity LHC. The pixel sizes are 50 50 µm2 with 1 readout column, and 25 100 µm2 with 1 or 2 readout columns (1E and 2E). Owing to the small inter-electrode distance, ranging from ∼28 µm to ∼51 µm in the considered layouts, these devices are expected to be extremely radiation hard. TCAD simulations by Synopsys Sentaurus, incorporating advanced radiation damage models, have been used for the design/optimization of these new 3D pixel sensors. In this study, we have compared the accuracy of different bulk damage models in predicting the signal efficiency of small-pitch 3D sensors irradiated at large fluences and its evolution with the bias voltage at different positions within the 3D cell. Selected simulation results will be reported in comparison to experimental data.