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.