Demonstration, radiation tolerance and design on a betavoltaic micropower

The limitation of conventional silicon P+/I(N−)/N+ junction device coupled with 63Ni radioactive source as a betavoltaic micropower is further investigated both theoretically and experimentally. The radiation tolerance of the devices irradiated by a 2.2 mCi 63Ni with fluence up to 1.5 × 1015 cm−2 is demonstrated by I–V, C–V measurements and the electrical output of device under irradiation by an 8 mCi 63Ni is measured and calculated. An approach is performed which describes the β-particles energy deposition distribution within silicon junction device and the results illustrate significant influence on the energy conversion efficiency due to the incompatibility of the energy deposition distribution relied on structure configuration. The test result is also compared with the experimental data of Wisconsin University and the major factors causing low energy transfer efficiency are analyzed. Some means such as multi-hole Si/SiC heterojunction structure, cylindrical radioactive volumetric source, narrowed depletion region width and keeping the leakage current with an order of magnitude of picoampere are adopted and ultimately structure parameters such as hole diameter, radioactive source thickness, depletion region width are determined and discussed, in order to absorb effectively a significant number of energetic particles and limit the radiation degradation at the same time and thus enhance the energy conversion efficiency.