NIEL DOSE and DLTS Analyses on Triple and Single Junction solar cells irradiated with electrons and protons

TL;DR

This study evaluates the radiation tolerance of triple and single junction solar cells using NIEL dose and DLTS spectroscopy, revealing degradation patterns and defect characteristics after electron and proton irradiation.

Contribution

It provides new insights into the defect mechanisms in multi-junction solar cells under space radiation using combined NIEL dose and DLTS analysis.

Findings

Degradation of InGaP and GaAs cells after electron radiation.

High variability in remaining factors after proton irradiation.

Correlation between DLTS defect signals and Displacement Damage Dose.

Abstract

Space solar cell radiation hardness is of fundamental importance in view of the future missions towards harsh radiation environment (like the Jupiter missions) and for the new spacecraft using Electrical Propulsion. In this paper we report the radiation data for triple junction (TJ) solar cells and related component cells. Triple junction solar cells, InGaP top cells and GaAs middle cells degrade after electron radiation as expected. With proton irradiation, a high spread in the remaining factors was observed, especially for the TJ and Ge bottom cells. Radiation results have been analyzed by means of the Displacement Damage Dose method and DLTS spectroscopy. In particular with DLTS spectroscopy it was possible to analyze the nature of a few defects introduced by irradiation inside the GaAs sub cell observing a strong correlation with the Displacement Damage Dose.