Radiation resistant LGAD design

TL;DR

This study investigates the radiation resistance of various LGAD detector designs with different doping strategies, revealing the effects of neutron and proton irradiation on their performance and the influence of doping materials and methods.

Contribution

It introduces new LGAD designs with diverse doping combinations and compares their radiation resistance, highlighting the impact of doping type, implant width, and irradiation type on detector durability.

Findings

Gallium-doped LGADs are more affected by initial acceptor removal than Boron-doped ones.

Carbon presence reduces initial acceptor removal for both Gallium and Boron doping.

Proton irradiation causes at least twice as much initial acceptor removal as neutron irradiation.

Abstract

In this paper, we report on the radiation resistance of 50-micron thick LGAD detectors manufactured at the Fondazione Bruno Kessler employing several different doping combinations of the gain layer. LGAD detectors with gain layer doping of Boron, Boron low-diffusion, Gallium, Carbonated Boron and Carbonated Gallium have been designed and successfully produced. These sensors have been exposed to neutron fluences up to $\phi_n \sim 3 \cdot 10^{16}\; n/cm^2$ and to proton fluences up to $\phi_p \sim 9\cdot10^{15}\; p/cm^2$ to test their radiation resistance. The experimental results show that Gallium-doped LGADs are more heavily affected by initial acceptor removal than Boron-doped LGAD, while the presence of Carbon reduces initial acceptor removal both for Gallium and Boron doping. Boron low-diffusion shows a higher radiation resistance than that of standard Boron implant, indicating a dependence of the initial acceptor removal mechanism upon the implant width. This study also demonstrates that proton irradiation is at least twice more effective in producing initial acceptor removal, making proton irradiation far more damaging than neutron irradiation.