3D GaN-based betavoltaic device design with high energy transfer efficiency

Area of Science:

• Semiconductor Physics
• Nuclear Engineering
• Materials Science

Background:

• Betavoltaic (BV) devices offer a promising route for long-term power generation.
• Enhancing energy transfer efficiency (ηsrc) and power density (P_GaN/cm²) are critical for BV device viability.
• Gallium Nitride (GaN) is a key material for advanced semiconductor applications, including energy conversion.

Purpose of the Study:

• To develop and demonstrate a combined 3D core-shell and planar pin structure for GaN betavoltaic devices.
• To maximize energy transfer efficiency from the source and power generated per cm².
• To optimize device dimensions and source integration for superior performance.

Main Methods:

• Utilized physics-based Sentaurus TCAD and Monte Carlo N-Particle extended (MCNPX) software for simulations.
• Conducted a parametric study of device dimensions, including mesa width, height, and separation.
• Employed a ⁶³NiCl₂ radioisotope source for energy transfer analysis.

Main Results:

• Determined optimal GaN pin core-shell mesa dimensions: 2 µm wide and 4 µm tall.
• Identified a 2 µm gap for conformal ⁶³Ni source surrounding for maximum η_src.
• Achieved a 3.75x increase in P_GaN/cm² with 5.82x improvement in η_src at 10 µm mesa separation.

Conclusions:

• The 3D GaN core-shell structure significantly outperforms planar designs in betavoltaic applications.
• Optimized device geometry and source integration are crucial for maximizing BV device efficiency and power density.
• This advanced structure holds high potential for next-generation radioisotope power sources.