Characterization of LGAD sensors and development of a TPA-TCT system

by Moritz Oliver Wiehe (Albert Ludwigs Universitaet Freiburg (DE))

Wednesday 7 Jul 2021, 11:00 → 12:00 Europe/Zurich

CERN

Low Gain Avalanche Detectors (LGAD) are a promising technology in the field of ultra fast timing detectors.
To investigate the relation between the onset of multiplication and the depletion of the amplification layer and the change of gain after irradiation and annealing, LGADs were irradiated with 24 GeV/c-protons to a fluence of 1 × 10^14 n_eq/cm^2 and annealed at 60°C. Transient-Current-Technique (TCT), edge-TCT, IV and CV measurements were carried out after consecutive annealing steps. After a reduction of gain after irradiation, no effect of annealing was observed.
The onset voltage of charge multiplication, measured with TCT, changes with annealing and is believed to be related to a change in the electric field profile inside the bulk of the sensor.
Furthermore, the latest status of the development of a Two Photon Absorption - Transient Current Technique (TPA-TCT) setup will be presented.
In recent years a novel method, TPA-TCT, based on the charge carrier generation by absorption of two photons, was developed. TPA-TCT proved to be very useful in 3D characterization of silicon devices with unprecedented spatial resolution. Currently the first compact TPA-TCT setup is under development at CERN. After a revision of the laser system, commissioning is now in the final stage. The current status of the setup and first measurements will be presented.

 

DTseminar_TPA-TCT_mwiehe.pdf