A Compensated Design of the LGAD Gain Layer

TL;DR

This paper introduces a novel LGAD gain layer design using overlapping p+ and n+ implants to enhance radiation resilience and maintain gain at higher fluences, improving 4D tracking capabilities.

Contribution

The proposed compensated gain layer design is a new approach that maintains gain under irradiation by balancing acceptor and donor doping.

Findings

The new design maintains gain after higher irradiation fluences.

It offers improved radiation hardness over standard LGADs.

Enhanced 4D tracking potential at high fluences.

Abstract

In this contribution, we present an innovative design of the Low-Gain Avalanche Diode (LGAD) gain layer, the p$^+$ implant responsible for the local and controlled signal multiplication. In the standard LGAD design, the gain layer is obtained by implanting $\sim$ 5E16/cm$^3$ atoms of an acceptor material, typically Boron or Gallium, in the region below the n$^{++}$ electrode. In our design, we aim at designing a gain layer resulting from the overlap of a p$^+$ and an n$^+$ implants: the difference between acceptor and donor doping will result in an effective concentration of about 5E16/cm$^3$, similar to standard LGADs. At present, the gain mechanism of LGAD sensors under irradiation is maintained up to a fluence of $\sim$ 1-2E15/cm$^2$, and then it is lost due to the acceptor removal mechanism. The new design will be more resilient to radiation, as both acceptor and donor atoms will undergo removal with irradiation, but their difference will maintain constant. The compensated design will empower the 4D tracking ability typical of the LGAD sensors well above 1E16/cm$^2$.