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Description
This work investigates the impact of irradiation on the timing performance of 3D silicon devices and electric field and charge collection uniformity. The study is organized in two parts. First, the response of irradiated and non-irradiated double-sided 3D CNM devices is compared. Second, the performance of a 3D IMECAS device is analyzed when un-irradiated and irradiated; this device incorporates a 2 μm wide square trench electrode and a central electrode with a diameter of 0.5 μm.
The results highlight two main effects. First, irradiation reduces the influence of geometrically induced low-field regions, thereby suppressing the slow component of charge collection and significantly shortening the long tails observed in the signal waveforms. This leads to an improvement in timing response. Second, although irradiation decreases the signal amplitude, this loss can be compensated by the higher electric field developed in the device, which enhances charge multiplication in 3D IMECAS devices with gain. This effect is an intrinsic feature of 3D geometries with very small electrode radii, where strong local electric fields can be established. Despite the high electric field near the electrode tip, in the 3D Imecas device, the device remains stable due to a self-quenching mechanism that limits the multiplication process. These results indicate that, irradiation can mitigate detrimental waveform components while preserving stable operation and improving timing performance.