Demonstration of a High Open-Circuit Voltage GaN Betavoltaic Microbattery

A high open-circuit voltage betavoltaic microbattery based on a GaN p-i-n diode is demonstrated. Under the irradiation of a 4×4 mm² planar solid ⁶³Ni source with an activity of 2 mCi, the open−circuit voltage V_oc of the fabricated single 2×2 mm² cell reaches as high as 1.62 V, the short−circuit current density J_sc is measured to be 16nA/cm². The microbattery has a fill factor of 55%, and the energy conversion efficiency of beta radiation into electricity reaches to 1.13%. The results suggest that GaN is a highly promising potential candidate for long-life betavoltaic microbatteries used as power supplies for microelectromechanical system devices.