Demonstration of high efficient SiC betavoltaics for Ni-63 radioisotope battery

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Byoung Gun Choi, Kyung Hwan Park, Seongmo Park, Taewook Kang, Young-Mok Yun, KyeongSu Jeon, Kwang Jae Son and Jin Joo Kim

Electronics and Telecommunications Research Institute, South Korea
Nano Convergence Practical Application Center, South Korea
Korea Atomic Energy Research Institute, South Korea

: J Nucl Ene Sci Power Generat Technol

Abstract

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Radioisotope batteries have several advantages compared to other chemical batteries in energy storage and life time. Among the various radioisotopes, pure beta-emitting isotopes such as Ni-63, Pm-147, and H-3 can be easily shielded for safety and have long half-life from several to a hundred years. The use of long half-life beta-emitting radioisotopes as a source of batteries seems to solve all inconveniences in recharging portable personal electronic devices, such as mobile phone, and enormous kinds of wireless computer peripherals. Unfortunately, the long life and high output power cannot be satisfied at the same time with betavoltaic batteries because the energy density of a radioisotope is inversely proportional to the half-life of the isotope. Thus a lot of effort has gone into increasing the conversion efficiency of betavoltaic batteries by using wide bandgap semiconductors. In this paper, we use wide bandgap SiC semiconductor for Ni-63 betavoltaic. The PIN SiC betavoltaic structure consists of low resistive (0.015~0.025 ohm-cm) n-type SiC substrate, low doped (3.5x1015/cm3) n-type SiC absorption layer, and highly doped (1x1019/cm3) p-type SiC layer. The thickness of the each layers are 500 μm, 20 μm, and 0.25 μm, respectively. The demonstrations of the SiC betavoltaic batteries are performed by using 17 keV electron beam, which energy is equal to the average energy of beta particles irradiated from Ni-63. Under the electron beam power of 11.9 μW (700pA@17keV), the betavoltaic shows a short circuit current of 1.02 μA, an open circuit voltage of 2.34 V and the maximum output power of 2.1 μW. Fill-factor of the device is 0.87 and the power conversion efficiency is as high as 17.5%. Also the demonstration of the Ni-63 mounted betavoltaic shows a short circuit current of 3.73 nA and an open circuit voltage of 1.97 V resulting a conversion efficiency of 7.9% and output power of 45.7 nW/cm2 under incident radioactivity of 0.9 mCi Ni-63 beta-ray.

Biography

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Email: cbgun@etri.re.kr