Investigation of p-Type Silicon Heterojunction Radiation Hardness

The space sector is facing significant upheavals, in particular, in terms of cost reduction challenges, driven by the emergence of low Earth orbit constellations. Concerning solar power generation, it opens up perspectives for alternative solar photovoltaics technologies, instead of the highly performant and expensive III-V multijunction devices. Crystalline silicon solar cells, which have fueled initial space developments, spark a renewed interest, thanks to their industrial maturity, high efficiencies on p-type substrates, and costs of two to three orders of magnitude lower than those of III-V. In this context, we present here the results of electrons radiation hardness studies on p-type (Ga-doped) silicon heterojunction solar cells. Devices with thicknesses down to 60 μm are manufactured and then characterized before and after 1MeV electrons irradiations. The best ultra-thin heterojunction cell shows an end-of-life (1.5 × 10
¹⁴
e/cm
²
) externally certified efficiency of 15.9% under AM1.5G at room temperature; this translates into ∼ 14.3% with AM0 spectrum. The benefits of thickness reduction with respect to radiation hardness are presented, and the cells’ improvement pathways discussed.