Speaker
Description
Future hadronic colliders are expected to have increasing multiple interactions per bunch crossing, which poses a challenge for silicon detectors. These sensors need to perform 4D tracking and withstand extreme radiation levels.
Low-gain avalanche diodes have excellent timing performance but also a moderate fluence limit. Beyond about $2.5\cdot10^{15}$ $n_{eq}/cm^2$, the gain implant, which allows for rapid signals and, thus, timing resolutions of $\mathcal{O}$(10 ps), becomes completely deactivated due to acceptor removal.
However, it is possible to overcome this limitation by innovatively realizing the gain layer as the compensation of two implants of opposite dopant species. Both profiles undergo doping removal, but if adequately engineered, their difference will remain constant as the fluence increases, thus extending 4D tracking to fluences of $\mathcal{O}$($10^{17}$ $n_{eq}/cm^2$).
In this contribution, we propose an alternative use of van der Pauw (vdP) structures to achieve this goal. Generally used by foundries to verify the effectiveness of implantation processes, we will instead use them to study the evolution of doping with fluence. By comparing TCAD simulations and experimental measurements, pre- and post-irradiation, we will extract the acceptor and donor removal coefficients of the two compensated gain layer implants, having a vdP for each of them. This information will allow the engineering of the two profiles for the second production of Compensated LGADs.
