Characterization of Low Gain Avalanche Detector Prototypes’ Response to Gamma Radiation

Abstract

Motivated by the need for fast timing detectors to withstand up to 2 MGy of ionizing dose at the High Luminosity Large Hadron Collider, prototype low gain avalanche detectors (LGADs) have been fabricated in a single pad configuration, 2 × 2 arrays, and related p-i-n diodes, and exposed to Co-60 sources for study. Devices were fabricated with a range of dopant layer concentrations, and for the arrays, a variety of inter-pad distances and distances from the active area to the edge. Measurements of capacitance versus voltage and leakage current versus voltage have been made to compare pre- and post-irradiation characteristics in gain layer depletion voltage, full bulk depletion voltage, and breakdown voltage. Conclusions are drawn regarding the effects of the gammas on both surface and interface states and on their contribution to acceptor removal through non-ionizing energy loss from Compton electrons or photoelectrons. Comparison of the performances of members of the set of devices can be used to optimize gain layer parameters.

Characterization of the response of IHEP-IME LGAD with shallow carbon to Gamma Irradiation

“…For this study, the reference operating voltage is selected at 85 V. The R of all samples are shown in figure 8 10 9 Ω, which is two orders of magnitude higher than the non-carbon-doped HPK LGAD irradiated to 2.5 MGy, where R decreases by four orders after irradiation [8]. HPK's LGAD also features a passivation layer.…”

“…Multiple institutes, including BNL, FBK, and NDL, have conducted studies on LGADs, investigating the effects of bulk damage caused by irradiation and observing numerous adverse effects on LGAD performance [6,7,14]. However, there has been limited research on surface damage specifically related to LGADs with carbon implantation [8]. This study aims to investigate the surface damage induced by gamma-ray irradiation on LGADs with shallow carbon implantation.…”