The electric field distribution and charge drift currents in Si particle detectors are analyzed. Profiling of the injected charge drift current transients has been implemented by varying charge injection position within a cross-sectional boundary of the particle detector. The obtained profiles of the induction current density and duration of the injected charge drift pulses fit well the simulated current variations. Induction current transients have been interpreted by different stages of the bipolar and monopolar drift of the injected carriers. Profiles of the injected charge current transients registered in the non-irradiated and neutron irradiated Si diodes are compared. It has been shown that the mixed regime of the competing processes of drift, recombination, and diffusion appears in the measured current profiles on the irradiated samples. The impact of the avalanche effects can be ignored based on the investigations presented. It has been shown that even a simplified dynamic model enabled us to reproduce the main features of the profiled transients of induced charge drift current.

The problem of pulsed current signals in capacitor type sensors, due to drifting surface charge domain is considered for the analysis of the operational characteristics in photo-and particle-detectors. In this article, the models of the formation of the pulsed currents have been analyzed in vacuum and dielectric filled capacitor-like detectors. Injected charge drift regimes such as Shockley-Ramo's-type (large charge drift) and free flight within Coulomb's force field (small charge drift) are discussed. It has been shown that solutions of the injected charge drift in the vacuum gap capacitor can be employed to emulate charge drift over free path in dynamic solution of the problem with scattering. Pulsed current signals and charge drift in the detectors of the capacitor filled with dielectric type have been analyzed, where the bipolar charge injection and various drift regimes appear. The bipolar carrier drift transformation to a monopolar one is considered, after either electrons or holes, injected within the material, reach the external electrode. The impact of the dynamic capacitance and load resistance in the formation of drift current transients is highlighted. It has been illustrated that the synchronous action of carrier drift, trapping, generation and diffusion can lead to a vast variety of possible current pulse waveforms.

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The operation dynamics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the software package Synopsys TCAD Sentaurus. The monopolar and bipolar drift regimes have been analyzed by using dynamic models based on the Shockley-Ramo theorem. The carrier multiplication processes determined by impact ionization have been considered in order to compensate carrier lifetime reduction due to introduction of radiation defects into GaN detector material.

In order to evaluate carrier densities created by 1.6 MeV protons and to trace radiation damage of the 2.5 μm thick GaN epi-layers grown by metalorganic chemical vapor deposition technique, a correlation between the photoconductivity transients and the steady-state photoluminescence spectra have been examined. Comparison of luminescence spectra induced by proton beam and by laser pulse enabled us to evaluate the efficiency of a single proton generation being of 1 × 107 cm−3 per 1.6 MeV proton and 40 carrier pairs per micrometer of layer depth. This result indicates that GaN layers can be an efficient material for detection of particle flows. It has been demonstrated that GaN material can also be a rather efficient scintillating material within several wavelength ranges.