Boron-Doped Single-Crystal Diamond: The Optimal Candidate Material for Nuclear Batteries with High Open-Circuit Voltage

The application of Micro-Electro-Mechanical Systems (MEMS) in extreme environments is becoming increasingly widespread, such as in portable medical devices and deep-sea detectors. This type of equipment is extremely small in size and usually operates in a low-duty-cycle pulse mode, which imposes requirements on power sources: small size, long lifespan, and stable reliability. Traditional solar cells and lithium batteries have shortcomings in terms of miniaturization, environmental adaptability, and lifespan. In contrast, nuclear batteries are regarded as ideal long-term micro power sources due to their immunity to environmental influences and high energy density.

Among numerous semiconductor materials, diamond is considered the optimal candidate material for realizing nuclear batteries with high open-circuit voltage, thanks to its ultra-wide bandgap (5.5 eV), strong radiation resistance, and high carrier mobility. However, traditional diamond nuclear batteries still face bottlenecks such as insufficient energy deposition, limited device structure, and difficulties in doping technology, resulting in performance that lags behind other wide-bandgap semiconductor devices. Nevertheless, stacked boron-doped diamond batteries, which adopt ⁶³Ni/Ni isotope electrodes with low energy loss, have solved these problems.

The main innovations include:

Stacked Heterojunction Structure: It breaks through the energy deposition saturation limitation of the traditional single vertical structure and improves the carrier collection efficiency.

Integrated Radioactive Source Electrode: By integrating ⁶³Ni with Ni, the energy loss caused by the self-absorption effect is significantly reduced.

Parameter Optimization Modeling: Combined with Monte Carlo and finite element simulations, this model takes into account the incomplete ionization of diamond, as well as the carrier migration and recombination characteristics, and optimizes the doping concentration and layer thickness.

Integrating this battery with an advanced Energy Management System (EMS) enables precise and stable regulation of pulse current output in the range of nA–mA. This design not only improves operational efficiency but also extends the service life.

Typical Application Scenarios:

Portable Smart Devices: Extremely small in size, only 1/1000 of that of traditional button batteries.

Implantable Medical Devices (e.g., cardiac pacemakers): A single implantation can meet the patient’s lifelong needs, eliminating the need for replacement surgery.

Extreme Environment Equipment (e.g., deep-sea acoustic beacons): Capable of stable operation in high-pressure and low-temperature environments, with a lifespan of up to 50 years.

This study proposes and verifies the p-diamond/n-Ga₂O₃ stacked heterojunction nuclear battery scheme for the first time. It addresses key issues such as low energy deposition efficiency and structural limitations, and realizes the design of a micro-nuclear battery with high voltage, high efficiency, and long lifespan. This provides a feasible long-term energy solution for MEMS devices, medical implants, and extreme environment equipment.

The boron-doped single-crystal diamond produced by CSMH can achieve doping from low concentration to high concentration. It has realized a uniform and controllable concentration and a customizable boron doping process.CSMH uses the MPCVD method to prepare large-sized and high-quality diamonds,and currently has mature products such as diamond heat sinks, diamond wafers, diamond windows,diamond hetero junction integrated composite substrates,etc.