Effects of shallow carbon and deep N++ layer on the radiation hardness of IHEP-IME LGAD sensors

Design and testing of LGAD sensor with shallow carbon implantation

“…The first version of LGAD sensors that IHEP developed with IME focused on optimizing the n ++ layer and the p + gain layer fabrication process [16,17]. A preliminary exploration of using shallow carbon implantation in the LGAD sensors was also included in IHEP-IMEv1 [12,18].…”

“…The IHEP-IMEv2 and IHEP-IMEv1 LGAD sensors [12] were irradiated with neutrons at the JSI nuclear research reactor in Ljubljana [19,20]. Three different irradiation fluences were used: 0.8×10 15 , 1.5×10 15 , and 2.5×10 15 n eq /cm 2 .…”

“…The lower sensor is used as the trigger for electrons signal in the beta telescope test. The signal pulses from both sensors are recorded by a digital oscilloscope with 2 GHz bandwidth and 40 GS/s sampling rate for offline analysis [12].…”

“…LGAD sensor, with low energy carbon implantation, has a stable gain layer in which the active boron concentration does not decrease with increasing carbon dose. Meanwhile, the IHEP-IMEv2 carbon-enriched LGAD sensor has the smallest acceptor removal constant among the IHEP-IME first version (IHEP-IMEv1) [12], FBK Ultra-Fast Silicon Detectors third version (UFSD3) [10], and Hamamatsu Photonics Kabushiki-gaisha 3.2 version (HPK3.2) [13] LGAD sensors, as shown in Table 1. This is reflected in the smallest excess voltage required to compensate for the gain loss due to radiation.…”