Characterization of FBK small-pitch 3D diodes after neutron irradiation up to 3.5x10**16 neq cm**-2

TL;DR

This study demonstrates that small-pitch 3D diodes maintain high signal efficiency and radiation tolerance even after extremely high neutron irradiation, confirming their suitability for high-radiation environments like the HL-LHC.

Contribution

The paper provides the first detailed characterization of small-pitch 3D diodes after neutron irradiation up to 3.5x10^16 neq/cm^2, highlighting their robustness and charge multiplication effects.

Findings

High signal efficiency at extreme fluences

Charge multiplication boosts performance at high voltage

Radiation tolerance exceeds HL-LHC requirements

Abstract

We report on the characterization by a position resolved laser system of small-pitch 3D diodes irradiated with neutrons up to an extremely high fluence of 3.5x10**16 neq cm**-2. We show that very high values of signal efficiency are obtained, in good agreement with the geometrical expectation based on the small values of the inter-electrode spacings, and also boosted by charge multiplication effects at high voltage. These results confirm the very high radiation tolerance of small-pitch 3D sensors well beyond the maximum fluences expected at the High Luminosity LHC.