LAUSR

An evolution of the transient characteristics of the GaN p-i-n diodes, operating in the avalanche mode and acting as particle sensors, has been simulated by using the Synopsys TCAD Sentaurus software package and the drift-diffusion approach. Profiling of the charge generation, recombination and drift-diffusion processes has been performed over a nanosecond time-scale with a precision of a few picoseconds and emulated through the 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 processes have been taken into account. Fast and slow components within a current transient have been analysed based on the consideration of the carrier spatial distribution at different instants of the avalanche process. The internal gain due to charge multiplication ensures the sufficient charge collection on electrodes of the relatively thin (5 µm) diode operating in the avalanche mode. It has been shown that the simulated evolution of the detector transient responses by employing the drift-diffusion approach reproduces properly the qualitative modifications of the main features of a detector with an internal gain, realized by induction of the avalanche processes governed by the applied external voltage.