Ab initio electronic stopping power for protons in Ga0.5In0.5P/GaAs/Ge triple-junction solar cells for space applications.

Natalia E Koval,Fabiana Da Pieve,Emilio Artacho

doi:10.1098/rsos.200925

Abstract

Motivated by the radiation damage of solar panels in space, firstly, the results of Monte Carlo particle transport simulations are presented for proton impact on triple-junction Ga0.5In0.5P/GaAs/Ge solar cells, showing the proton projectile penetration in the cells as a function of energy. It is followed by a systematic ab initio investigation of the electronic stopping power (ESP) for protons in different layers of the cell at the relevant velocities via real-time time-dependent density functional theory calculations. The ESP is found to depend significantly on different channelling conditions, which should affect the low-velocity damage predictions, and which are understood in terms of impact parameter and electron density along the path. Additionally, we explore the effect of the interface between the layers of the multilayer structure on the energy loss of a proton, along with the effect of strain in the lattice-matched solar cell. Both effects are found to be small compared with the main bulk effect. The interface energy loss has been found to increase with decreasing proton velocity, and in one case, there is an effective interface energy gain.

Highlights

With the new advancements in solar cell technology and the rapid expansion of space missions, understanding the key aspects royalsocietypublishing.org/journal/rsos R
The results presented here should contribute to understand to what extent channelling effects can be linked to both the electronic density and the atomic number of the element(s) in the compounds constituting the solar cell stack, which should serve as a basis to a further study of non-adiabatic MD simulations of cascades
The results in figure 4 clearly show that the coverglass lowers the fluences of lower energy particles, leaving almost unaffected the high-energy portion of the proton spectrum. Those protons are the primary impacting protons and those generated by the nuclear interactions in the target

Summary

Introduction

With the new advancements in solar cell technology and the rapid expansion of space missions, understanding the key aspects royalsocietypublishing.org/journal/rsos R. Soc. Open Sci. 7: 200925 2 contact. GaInP tunnel junctions 2 mm GaAs. Ge contact which link the macroscopic response of solar cells of current and future spacecraft to the fundamental processes of particle stopping inside the target has acquired new relevance. Solar cells are key components of spacecraft and satellites as they provide power for navigation, communication, data handling, thermal control and functioning of the instrumentation. The so-called triplejunction (TJ) solar cells, made of Ga0.5In0.5P, GaAs and Ge layers (see scheme in figure 1), are the state of the art for space applications, generally protected by an amorphous SiO2 coverglass. All layers are usually lattice-matched to the substrate (Ge)

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