Linking laser-induced and self-induced signals in double trench isolated LGADs: Implications for signal anomalies in interpad region

In this article, we present our research on the space-charge effects in segmented LGADs, specifically the interpad (IP) region, with a focus on double trench isolated LGADs (2Tr TI-LGADs). We found that the examined 2Tr sample showed different induced current signals in the IP region compared to previously studied sensors with different isolation structures. We identified two types of laser pulse induced signals in the IP region: “normal” signal, resembling corresponding pad signals, and “strong” signal represented by significantly broader waveforms with several times higher amplitude. In addition, randomly occurring “ghost” signal appearing in biased but not laser-illuminated sensors were identified during our study. All three types of signals were explored in terms of the influence of bias voltage and laser power at different temperatures. Possible explanations of the observed signals are discussed.