SiC Betavoltaic Battery Surface Area Optimization
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Solution Overview
Problem
Existing beta-voltaic devices using silicon-based materials have low power conversion efficiencies and are suboptimal for harnessing low-level radioisotope emissions, necessitating the development of novel device geometries and packaging to maximize radioisotope surface area utilization and power output.
Innovation Solution
The use of silicon carbide (SiC) as the semiconductor material in combination with innovative device configurations and packaging, such as circular and square geometries with parallel and series circuit designs, to enhance power density and efficiency, along with magnetic and electrical shielding to optimize radioisotope energy harvesting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based materials are used in beta-voltaic devices, then manufacturing is easier and cost is lower, but power conversion efficiency is significantly reduced
Solution Approach 1:
The patent changes the material parameter from silicon to silicon carbide, which has different physical properties including wider bandgap and higher radiation hardness. This parameter change resolves the contradiction by achieving both high power conversion efficiency (>30%) and reasonable manufacturability through established SiC substrate and epitaxy technologies
Solution Approach 2:
The patent employs silicon carbide as a composite semiconductor material that combines the benefits of wide bandgap physics with radiation hardness and low leakage currents. This composite material approach enables efficient harvesting of low-level beta emissions while maintaining device reliability in harsh environments
2Device complexity
If conventional device geometries are used, then device complexity is lower, but radioisotope surface area utilization is insufficient
Solution Approach 1:
The patent transitions from planar 2D device geometries to three-dimensional configurations including stacked layers and spherical arrangements. This dimensional change maximizes the radioisotope surface area in contact with the semiconductor, enabling efficient harvesting of beta emissions from all directions and achieving high power density
Solution Approach 2:
The patent implements nested configurations where multiple device layers are stacked or arranged concentrically, with inner layers surrounded by outer layers. This nesting approach maximizes space utilization and ensures comprehensive coverage of the radioisotope surface area, thereby increasing total power output
3Object-affected harmful factors
If radioisotope emission levels are low, then safety and shielding requirements are reduced, but power output is insufficient
Solution Approach 1:
The patent changes the semiconductor material parameter to silicon carbide, which has superior charge carrier mobility and lower leakage currents compared to silicon. This parameter change enables efficient collection and conversion of low-level beta emissions into usable electrical power, achieving >30% power conversion efficiency even at low emission rates
Solution Approach 2:
The patent creates multiple copies of the beta-voltaic device in stacked or array configurations. By replicating the active conversion elements, the system accumulates sufficient power output from low-level emissions while each individual device maintains safe operating conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in high power density betavoltaic batteries capable of producing several nanowatts to milliwatts of power with efficiencies exceeding 30%, suitable for powering low-power electronic devices like medical implants and sensor networks for extended periods.
Implementation Method 1
Beta-voltaic devices have very high energy density and utilize radioisotopes as a fuel source. Radioisotope emissions originate from within a few microns of a radioactive material's surface... SiC provides low leakage currents to effectively harvest low level emission rates from the isotope
Implementation Method 2
in addition to its radiation hardness and ability not to degrade over time at higher temperatures and in harsh environments, SiC provides low leakage currents
Data Source
AI summary
To increase total power in a betavoltaic device, it is desirable to have greater radioisotope material and/or semiconductor surface area, rather than greater radioisotope material volume. An example of this invention is a high power density betavoltaic battery. In one example of this invention, tritium is used as a fuel source. In other examples, radioisotopes, such as Nickel-63, Phosphorus-33 or promethium, may be used. The semiconductor used in this invention may include, but is not limited to, Si, GaAs, GaP, GaN, diamond, and SiC. For example (for purposes of illustration/example, only), tritium will be referenced as an exemplary fuel source, and SiC will be referenced as an exemplary semiconductor material. Other variations and examples are also discussed and given.