Effects of Shallow Carbon and Deep N++ Layer on the Radiation Hardness of IHEP-IME LGAD Sensors

Low-gain avalanche diode (LGAD) is the chosen technology for the ATLAS high-granularity timing detector (HGTD). According to previous studies, the acceptor removal effect due to the radiation and the single-event burnout (SEB) at high bias voltages are still a challenge for the LGAD. The Institute of High Energy Physics (IHEP), Beijing, China, cooperated with the Institute of Microelectronics (IME), Beijing, China, for the design and fabrication of the IHEP-IME LGAD sensors with shallow carbon and deep N++ layer to improve the radiation hardness of LGAD. After neutron irradiation up to 2.5 \times 10^{15}\,\,{\mathrm{ n}}_{\mathrm{ eq}} /cm 2 , the leakage current, the collected charge, and timing resolution of the three IHEP-IME sensors measured with a beta telescope setup meet the HGTD requirements ( < 125~\mu \text{A} /cm 2 , >4 fC, and