Speaker
Description
Radiation-hard silicon sensors used in high-energy physics experiments require a high electric field and are susceptible to surface breakdown at the edges of the planar sensors, especially at the tips of metal contacts or implants, where field peaks develop. These high-field regions, which are influenced by defects at the oxide interface and the geometry of the sensor, can give rise to avalanche breakdown. In addition, generation current can originate from interface states that contribute to surface current, as well as from regions with structural damage in the silicon crystal lattice at the dicing edge.
To investigate the contributions of these current-generation mechanisms and optimize the sensor performance, the edge region of an n$^+$-p-p$^+$ diode including the dicing edge was implemented in Synopsys TCAD to simulate its electrical behavior from 273 K to 333 K. IV and CV tests were simulated and compared to measurements, the influence of key factors—such as surface and edge defect concentrations—was assessed. Transient Current Technique (TCT) simulations were performed in TCAD together with Allpix Squared and compared to measurements. This allowed assessment of the distribution of the electric field and fidelity of its simulation. The results provide a qualitative picture of how and where specific defect types contribute to the leakage current and breakdown at the sensor edge, indicating venues for future studies to further improve understanding of the current-generation mechanisms in the edge region of silicon sensors.
