Gain-layer project

Gain-layer degradation from exposure to radiation limits the use of Low-Gain Avalanche Diodes (LGADs) in high energy particle physics detector experiments. Proper understanding of how the gain-layer is altered is not available on a defect level. Only measurements for materials with much lower effective doping concentrations are available. The direct study of the gain-layer is not possible with typical defect spectroscopy measurements like Thermally Stimulated Currents (TSC) and Deep-Level Transient Spectroscopy (DLTS). To combat this problem and gain a better understanding of the processes which degrade LGADs, the Gain-Layer Project was started. Within this project 19 050 diodes were produced with various Boron, Phosphorus, Oxygen and Carbon concentrations. The material used is low-resistivity p -type Silicon. The effective doping concentrations are in the order of typical LGAD gain-layers. These diodes will serve the defect community in the coming years for various studies. This article introduces this project with detailed descriptions of the diodes, their flavours and their processing, and reports on results from I – V , C – V , SIMS and DLTS measurements on unirradiated diodes.