Design and microfabrication of radioisotope micro battery based on MEMS

The principle, structure, and characteristics of ⁶³Ni radioisotope micro battery (RMB) were introduced. The equations of circuit current were established. Due to small surface area of the direct conversion device with the inverted triangle or pyramid structure in the traditional RMB, a direct conversion device with square arrays of vertical walls for RMB was designed to enlarge the surface area. The design for the structure of direct conversion device demonstrates that the best junction depth is about 2 μm-3 μm. A RMB was fabricated according to the above mentioned and its properties were measured. The results indicate that V_oc(open circuit voltage), J_SC(short circuit current density) and P_m(output power density) are respectively 127 mV, 4 nA/mm² and 0.41 nW/mm², which are in agreement with the expected values.