High open-circuit voltage nuclear batteries enabled by integrated stacked p-diamond/n-Ga₂O₃ heterojunction

Nuclear batteries, characterized by compact size, long lifetime, and high stability, serve as an alternative power source tailored for extreme environments. Their large-scale application, however, is hindered by high energy loss in radioactive sources and low energy conversion efficiency in energy converters. Diamond, with its strong radiation resistance, ultra-wide bandgap, and high carrier mobility, holds promise as the most viable energy converter material for nuclear batteries aiming for high open-circuit voltage. In this study, a p-diamond/n-Ga₂O₃ heterojunction betavoltaic nuclear battery is designed, incorporating an innovative stacked heterojunction structure and a low-energy-loss ⁶³Ni/Ni radioactive source electrode. Such a structural integration significantly enhances energy deposition and carrier collection efficiency. Through the optimization of semiconductor characteristics and key structural parameters, the battery achieves an open-circuit voltage of 3.06 V, a conversion efficiency of 12.8%, and a power density of 354 μW⋅ cm⁻³ under 200 mCi ⁶³Ni irradiation, surpassing previously reported wide-bandgap semiconductor nuclear batteries in output performance. Addressing the unique operational demands of low-duty-cycle pulse-mode micro-electromechanical systems in extreme environments, betavoltaic nuclear battery integrated with an advanced energy management system is proposed. This design enables the betavoltaic nuclear battery to regulate pulse current output precisely and stably within the nA-mA range, enhancing both operational efficiency and service life while enabling intelligent environmental monitoring and equipment fault diagnosis.