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Development of nuclear microbattery prototype based on Schottky barrier diamond diodes

We designed, fabricated, and tested for the first time a prototype of nuclear micropower battery with an overall active area about 15 cm2 consisted in 130 single cells based on Schottky barrier diamond diodes. Diodes selection for the battery assembly was performed on the basis of I–V curves measurements at electron beam irradiation in SEM. A typical energy conversion efficiency of each cell was about 4–6%. To characterize a battery prototype performance, we carried out photovoltaic measurements using different radioisotopes. Under irradiation by 63Ni source with activity of 5 mCi cm−2, the output power density of 3 nW cm−2 was obtained. Due to large energy loss of the emitted β particles in source itself, the total battery efficiency was only 0.6%. However, with the long‐lived 63Ni isotope, this already gives the battery specific energy of about 120 W · hr/kg, comparable with the commercial chemical cells. During experiments with high activity 90Sr–90Y source, no degradation was observed after 1,400 h of the radiation exposure. The maximum output power density of 2.4 µW cm−2 was achieved using 238Pu α source. The results display that synthetic diamond is a highly promising material for nuclear microbattery fabrication. A strategy to further cell optimization is also discussed.