Efficient modeling of plasma effect on the signal formation in planar silicon detectors

Abstract Modeling the interactive behavior of charge carriers is essential for accurately calculating a silicon detector’s response to highly ionizing particles. This work presents a simulation framework that considers the plasma effect of the excess charges on the electric field, and subsequently, the charge collection in fully depleted and over-depleted planar silicon detectors. The algorithm employs a nested mesh system that dynamically adapts to the evolving carrier distribution, balancing high spatial resolution with computational efficiency. The framework is validated against experimental data from high-purity silicon surface barrier detectors irradiated with 5.5 MeV alpha particles under varying electric fields and temperatures. Simulated current waveforms closely match laboratory measurements, with key signal features such as plasma time and peak time agreeing within 9%. Compared to conventional tools that neglect plasma effects, such as Garfield $$++$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>+</mml:mo> <mml:mo>+</mml:mo> </mml:mrow> </mml:math> , the proposed method yields significantly improved waveform predictions. Additionally, it achieves accuracy comparable to commercial TCAD tools (e.g., Silvaco) while requiring substantially less computational time and memory, owing to its efficient adaptive meshing strategy.