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Description
The self-induced signals in trench isolated LGADSs can be driven by the complex interplay of trench-induced defects, electric field distortions, and temperature-dependent carrier dynamics. This self-induced signal phenomenon could be also related to the interplay between the guard ring (GR), trenches, and the n+ bias ring (implanted between two trenches). Such complex relation of many inter-linked phenomena may also lead to the enhanced duration of the avalanche multiplication supported by the positive feedback of the electron impact ionization at the periphery of the gain layer and the hole impact ionization at the corner of the SiO2 trenches. To our best knowledge the tests to directly assess the effect of grounded GR on ghost signals have not been performed yet. In this contribution we present the first comparative study on Ti-LGAD samples with/without grounding the guard ring. The two distinctive experimental techniques are applied: I-V measurements using a probe station at the Institute of Physics at the Czech Academy of Science and the TCT technique at the ELI ERIC, ELI Beamlines.
