The future upgrading of detectors for the high luminosity colliders requests the detectors that are capable work in the conditions where fluence of neutrons exceeds 1e17 cm-2 (e.g., the forward callorimeter in CMS). We make an attempt to investigate the possibilities of GaN detectors that works at room and higher temperature.
The dynamic characteristics of the GaN p-i-n avalanche diodes have been simulated using a drift-diffusion model according to the software package Synopsys TCAD Sentaurus. Particle detection is emulated through photo-excitation of an excess carrier domain at different locations of the active volume of a diode. Shockley-Read-Hall (SRH), Auger and radiative recombination was taken into account. It has been shown that the pulse shape of a total current strongly depends on the excess carrier photo-injection location due to the considerable difference of the electron and hole saturation velocity and impact ionization coefficient in GaN. The internal gain due to charge multiplication ensures sufficient charge collection on electrodes of the relatively thin (5 micrometers) avalanche diodes. Our calculations show that the necessary charge collection exists even in the case of a very low carrier lifetime (about 10 ps).