Electric Field Measurement by Edge Transient Current Technique on Silicon Low Gain Avalanche Detector

TL;DR

This paper introduces the diffusion profile method, a new approach to measure electric fields in LGAD detectors using edge-TCT waveforms, validated through simulations and experiments.

Contribution

The novel diffusion profile method estimates electric field dispersion by analyzing carrier diffusion effects in edge-TCT signals, providing an alternative measurement technique.

Findings

The method accurately estimates electric field distribution in LGADs.

Simulation results match experimental data well.

The approach is feasible with existing edge-TCT setups.

Abstract

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 edge-TCT 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.