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T: Fachverband Teilchenphysik

T 61: Silicon trackers 3

T 61.8: Vortrag

Mittwoch, 6. März 2024, 17:45–18:00, Geb. 30.22: kl. HS B

Simulation and measurement of charge transport near the Si-SiO₂ interface of silicon sensors — Ingo Bloch¹, Ben Brüers¹, Heiko Lacker², •Peilin Li², Ilona Stefana Ninca¹, and Christian Scharf² — ¹Deutsches Elektronen-Synchrotron (DESY) — ²Humboldt Universität zu Berlin

Some of the n-in-p silicon sensors for the ATLAS Inner Tracker (ITK) strip detector show signs of early breakdown at high humidity. To investigate the breakdown mechanism, Transient Current Technique (TCT) measurements are conducted in the region between the sensor’s guard ring and edge ring, where the breakdown has been observed through hot-electron emission microscopy. Picosecond laser pulses of 660 nm photons are focused on the sensor surface, generating free electrons and holes near the surface. These free charges drift in the local electric field and induce transient currents, which are measured as a function of the laser position and the applied bias voltage. To reproduce the measurements, charge transport at the Si-SiO₂ interface has been implemented in the simulation framework Allpix Squared. The electric and weighting fields have been simulated with Synopsys Sentaurus TCAD. By comparing the measurements to the simulations, a qualitative estimation of the discrepancy between the TCAD-simulated and actual electric fields can be achieved. The results of this analysis help to validate the TCAD simulation against measurements and to gain understanding of surface TCT measurements in the guard ring region of sensors, enabling further exploration of the humidity dependence of surface breakdown.

Keywords: TCT; Transient simulation; Surface transport; Humidity sensitivity