Harnessing atomic decay to power devices for decades without a single recharge
Continuous Power
Decades-Long Lifespan
Atomic Energy Source
In a University of Maryland laboratory, a special type of diode, smaller than a fingernail, generates electricity from atomic decay. It could power your pacemaker for a lifetime without ever needing a charge.
We live in a world shackled by cords and chargers. The smartphones in our pockets, the sensors that monitor our environment, and the medical devices that sustain lives all share a common weakness: their batteries inevitably run out. But what if the key to breaking this cycle was not a better battery, but a fundamentally different one? Enter the world of betavoltaic microbatteries—devices that convert the energy from radioactive decay directly into electricity. Recent breakthroughs, particularly using the semiconductor gallium nitride (GaN), are turning this sci-fi concept into a tangible reality, promising a future where devices can run for decades, or even centuries, without a single recharge.
The working principle of a betavoltaic device is elegantly simple and shares a surprising kinship with solar panels. Just as a photovoltaic cell converts light particles (photons) into electricity, a betavoltaic cell converts high-energy electrons (beta particles) emitted by a safe radioactive isotope4 . When these beta particles strike a semiconductor material, they knock electrons loose, creating electron-hole pairs (EHPs). An internal electric field within the semiconductor, typically from a p-i-n junction, then sweeps these charges apart, generating a usable electric current2 4 .
Converts photons to electricity
Converts beta particles to electricity
Radioactive isotopes decay at a steady, predictable rate, providing a constant trickle of power for years.
The lifespan is determined by the half-life of its radioactive fuel. Some isotopes could theoretically power devices for millennia1 .
Not all semiconductors are suited for the harsh environment inside a nuclear battery. This is where Gallium Nitride (GaN) shines. GaN is a wide bandgap semiconductor, a trait that makes it exceptionally robust and efficient for this task5 .
| Property | Description | Benefit for Betavoltaic Batteries |
|---|---|---|
| Wide Bandgap (3.4 eV) | The energy needed to excite an electron from the valence to the conduction band is large5 . | Enables higher output voltages and allows operation at much higher temperatures without performance loss5 . |
| High Radiation Hardness | The material's crystal structure is highly resistant to damage from radiation5 . | The battery's own beta radiation causes minimal damage over time, ensuring long-term stability and performance2 . |
| High Breakdown Voltage | GaN can withstand very high electric fields before failing5 . | Allows for the design of robust device structures that can handle the energy of beta particles efficiently. |
Furthermore, by alloying GaN with aluminum to create AlGaN, engineers can fine-tune the bandgap to an even wider range. This customization can lead to a higher output power and increased efficiency by better matching the energy of the incoming beta particles4 .
GaN's wide bandgap makes it ideal not just for betavoltaics, but also for high-power electronics and LED technology.
AlGaN alloys allow engineers to fine-tune semiconductor properties for optimal beta particle energy conversion.
To understand how these batteries are built and tested, let's examine the pivotal work detailed in the study "Design and Characterization of p-i-n Devices for Betavoltaic Microbatteries on Gallium Nitride"4 .
The p-i-n GaN structure was grown on a substrate using Metalorganic Chemical Vapor Deposition (MOCVD), a standard technique for producing high-quality semiconductor thin films4 .
The layered material was processed into specific devices for testing.
The diodes were first tested with standard current-voltage (I-V) measurements in the dark. This "dark current" measurement established a baseline performance, showing a turn-on voltage of about 3.4 V4 .
Instead of immediately using a radioactive isotope, the team employed an electron beam to simulate the effect of a beta source. This safe and controlled method allowed them to precisely evaluate the betavoltaic potential at energy levels equivalent to two common isotopes: Tritium (³H) with an average energy of 5.6 keV and Nickel-63 (⁶³Ni) with an average energy of 17 keV4 .
The experiments were a success. The GaN p-i-n diodes demonstrated a clear betavoltaic effect, generating electricity directly from the electron beam.
| Simulated Isotope | Average Electron Energy | Output Power | Conversion Efficiency |
|---|---|---|---|
| Tritium (³H) | 5.6 keV | 70 nW | 1.2% |
| Nickel-63 (⁶³Ni) | 17 keV | 640 nW | 4.0% |
| Design Parameter | Variation | Effect on Output Power |
|---|---|---|
| Height of i-GaN | Increased (e.g., to 700 nm) | Increased |
| Doping of i-GaN | Decreased (e.g., to 1×10¹⁶ cm⁻³) | Increased |
| Material Defects | High acceptor-like traps | Significantly Decreased |
Higher-energy beta particles lead to significantly better performance. The power output and conversion efficiency for the 17 keV Ni-63 simulation were nearly an order of magnitude higher than for the lower-energy Tritium simulation4 .
Creating a betavoltaic cell is a multidisciplinary effort, requiring specialized materials and isotopes. The following toolkit outlines the essential components used in the featured experiment and the broader field.
Tritium (³H) or Nickel-63 (⁶³Ni). These "fuel" the battery by emitting beta particles4 .
Metalorganic Chemical Vapor Deposition (MOCVD). Used to grow high-quality crystalline layers4 .
Current-Voltage (I-V) Measurement. Used to characterize diode performance4 .
The journey of betavoltaic batteries from the lab to our daily lives is accelerating. Researchers worldwide are building on the foundational work with GaN. In 2025, a team proposed three universal "figures of merit" — capture efficiency, gain, and gain efficiency — to standardize how betavoltaic performance is measured and compared6 .
Pacemakers and neural stimulators that last a patient's lifetime, eliminating risky replacement surgeries1 .
Maintenance-free sensors for IoT networks, monitoring infrastructure, environment, or security in remote locations for decades.
While betavoltaic batteries won't be powering our smartphones tomorrow, they are poised to fill the critical gaps that lithium-ion technology cannot. By harnessing the steady decay of the atom, we are on the cusp of creating a truly set-and-forget power source.