Radiation hardness studies of InGaAs and Si photodiodes at 30, 52, & 98 MeV and fluences to 5x10^11 protons/cm^2

TL;DR

This study evaluates the radiation tolerance of commercial InGaAs and Si photodiodes exposed to high-energy protons, revealing damage patterns and stability in responsivity at various fluences relevant for space and nuclear applications.

Contribution

It provides the first comprehensive comparison of InGaAs and Si photodiodes' radiation effects at multiple proton energies and fluences, with measurements traceable to NIST standards.

Findings

Si photodiodes' responsivity decreases with fluence

InGaAs photodiodes' dark current increases with fluence

No broadband degradation observed in InGaAs responsivity

Abstract

Here we report the results of an investigation into the effects of ionizing radiation on commercial-off-the-shelf InGaAs and Si photodiodes. The photodiodes were exposed to 30, 52, and 98 MeV protons with fluences ranging from 10^8 - 5x10^11 protons/cm^2 at the Indiana University Cyclotron Facility. We tested the photodiodes for changes to their dark current and their relative responsivity as a function of wavelength. The Si photodiodes showed increasing damage to their responsivity with increasing fluence; the InGaAs photodiodes showed significantly increased dark current as the fluence increased. In addition, we monitored the absolute responsivity of the InGaAs photodiodes over their entire bandpass. Our measurements showed no evidence for broadband degradation or graying of the response at the fluences tested. All measurements in this investigation were made relative to detectors traceable to NIST standards.