Modeling Charge Cloud Dynamics in Cross Strip Semiconductor Detectors

Abstract

When a $\gamma$-ray interacts in a semiconductor detector, the resulting electron-hole charge clouds drift towards their respective electrodes for signal collection. These charge clouds will expand over time due to both thermal diffusion and mutual electrostatic repulsion. Solutions to the resulting charge profiles are well understood for the limiting cases accounting for only diffusion and only repulsion, but the general solution including both effects can only be solved numerically. Previous attempts to model these effects have taken into account the broadening of the charge profile due to both effects, but have simplified the shape of the profile by assuming Gaussian distributions. However, the detailed charge profile can have important impacts on charge sharing in multi-electrode strip detectors. In this work, we derive an analytical approximation to the general solution, including both diffusion and repulsion, that closely replicates both the width and the detailed shape of the charge profiles. This analytical solution simplifies the modeling of charge clouds in semiconductor strip detectors.

Accepted for publication in Nuclear Instruments and Methods in Physics Research A

References in corpus (4)

• Benchmarking simulations of the Compton Spectrometer and Imager with calibrations
• Cadmium Zinc Telluride Detectors for a Next-Generation Hard X-ray Telescope
• The Compton Spectrometer and Imager Project for MeV Astronomy
• Optimization study of the electrode design of a 5 mm thick orthogonal-strip CdZnTe detector system