Electric field measurement by edge transient current technique on silicon low gain avalanche detector

A novel methodology, named the diffusion profile method, is proposed in this research to measure the electric field of a low gain avalanche detector (LGAD). The proposed methodology utilizes the maximum of the time derivative of the edge transient current technique (edge-TCT) test waveform to quantify the dispersion of the light -induced carriers. This method introduces the estimation of the elongation of the carrier cluster caused by diffusion and the divergence of the electric field force during its drift along the detector. The effectiveness of the diffusion profile method is demonstrated through the analysis of both simulated and measured edgeTCT waveforms. Experimental data was collected from a laser scan performed on an LGAD detector along its thickness direction. A simulation procedure has been developed in RASER (RAdiation SEmiconductoR) to generate signals from LGAD. An assumption of immediate one-step carrier multiplication is introduced to simplify the avalanche process. Simulation results were compared with transient current data at the waveform level and showed a favorable match. Both simulation and experimental results have shown that the diffusion profile method could be applied to certain edge-TCT facilities as an alternative of electric field measurement.