Speaker
Description
We present the results from a new batch of silicon sensors with internal gain produced by the Fondazione Bruno Kessler (FBK, Italy). The sensors are p-in-n Low-Gain Avalanche Diodes, in which the high-concentration implant responsible for signal multiplication is formed by an n-type dopant (nLGAD). The nLGADs are made on thin epitaxial-type substrates, with an active thickness of 55 $\mu$m. A brand-new design of the p$^{++}$ ohmic contact and the n$^+$ gain implant has been implemented to account for the activation and diffusion of the dopant elements used in the batch. Fourteen different wafers are produced, with different diffusion and depths for the two implants, and two different dopants, namely Phosphorus and Arsenic. Moreover, an extensive R&D on the peripheral structures optimised for n-type thin substrates has been included in the batch. The nLGAD sensors will provide unique information on the donor removal mechanism at a concentration of about 10$^{16}$ atoms/cm$^2$. This study will provide crucial knowledge for the design of the p$^+$-n$^+$ compensated LADs in the path to the extreme fluences. Moreover, nLGAD sensors are a valuable tool for detecting low-energy photons. Preliminary results on the sensors characterisation before and after irradiation will be presented and discussed.