A compensated design of the LGAD gain layer

In this contribution, we present an innovative design of the Low-Gain Avalanche Diode (LGAD) gain layer, the p+ implant responsible for the local and controlled signal multiplication. In the standard LGAD design, the gain layer is obtained by implanting ∼5E16/cm3 atoms of an acceptor material, typically Boron or Gallium, in the region below the n++ electrode. In our design, we aim at designing a gain layer resulting from the overlap of a p+ and an n+ implants: the difference between acceptor and donor doping will result in an effective concentration of about 5E16/cm3, similar to standard LGADs. At present, the gain mechanism of LGAD sensors under irradiation is maintained up to a fluence of ∼1–2E15/cm2, and then it is lost due to the acceptor removal mechanism. The new design will be more resilient to radiation, as both acceptor and donor atoms will undergo removal with irradiation, but their difference will maintain constant. The compensated design will empower the 4D tracking ability typical of the LGAD sensors well above 1E16/cm2.