Abstract
We model laser-induced transient-current waveforms in radiation coplanar-grid detectors. Poisson's equation is solved by the finite-element method and currents induced by a photogenerated charge are obtained using the Shockley-Ramo theorem.
The spectral response on a radiation flux is modeled by Monte Carlo simulations. We show a 10x improved spectral resolution of the coplanar-grid detector using differential signal sensing.
We model the current waveform dependence on the doping, depletion width, diffusion, and detector shielding, and their mutual dependence is discussed in terms of detector optimization. The numerical simulations are successfully compared to experimental data, and further model simplifications are proposed.
The space charge below electrodes and a nonhomogeneous electric field on a coplanar-grid anode are found to be the dominant contributions to laser-induced transient-current waveforms.