Simulation of the 3-D Coulomb Explosion of the Electron-Hole Distribution at High Injection Levels in 2-D Semiconductor Detectors

We developed a novel simulation code for 3-D electron-hole transport and signal formation in semiconductor detectors. The code includes thermal diffusion and Coulomb interaction between the carriers - essential for the correct simulation of high-density ionization tracks. The present work focuses on dedicated numerical techniques to correctly simulate the explosion of high-density charge carrier clouds down to the first instants of the time evolution, when extremely high field intensities are reached due to Coulomb interaction between carriers. The case study of a p+nn+ diode irradiated by 1 keV photons on under different bias and charge injection conditions up to 107 e.h pairs is presented and discussed. This case well represents the operating conditions foreseen in the imaging detectors for the novel FEL X-ray facilities and the potential of the developed simulation code.