  Next generation Low Gain Avalanche Diodes (LGAD) produced by Hamamatsu
photonics (HPK) and Fondazione Bruno Kessler (FBK) were tested before and after
irradiation with ~1MeV neutrons at the JSI facility in Ljubljana. Sensors were
irradiated to a maximum 1-MeV equivalent fluence of 2.5E15 Neq/cm2. The sensors
analysed in this paper are an improvement after the lessons learned from
previous FBK and HPK productions that were already reported in precedent
papers. The gain layer of HPK sensors was fine-tuned to optimize the
performance before and after irradiation. FBK sensors instead combined the
benefit of Carbon infusion and deep gain layer to further the radiation
hardness of the sensors and reduced the bulk thickness to enhance the timing
resolution. The sensor performance was measured in charge collection studies
using \b{eta}-particles from a 90Sr source and in capacitance-voltage scans
(C-V) to determine the bias to deplete the gain layer. The collected charge and
the timing resolution were measured as a function of bias voltage at -30C.
Finally a correlation is shown between the bias voltage to deplete the gain
layer and the bias voltage needed to reach a certain amount of gain in the
sensor. HPK sensors showed a better performance before irradiation while
maintaining the radiation hardness of the previous production. FBK sensors
showed exceptional radiation hardness allowing a collected charge up to 10 fC
and a time resolution of 40 ps at the maximum fluence.
