SiC PN Radioisotopic Battery Passivation for Surface Recombination Loss
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Solution Overview
Problem
Current silicon carbide PN-type radioisotopic batteries using H-3 face significant challenges in minimizing surface recombination loss of irradiation-generated carriers due to the shallow electron range of H-3, which limits output power and efficiency, and the processing technology for SiC materials is less developed compared to silicon, complicating the enhancement of energy conversion efficiency.
Innovation Solution
The design incorporates an H-3 silicon carbide PN-type radioisotopic battery structure with an N-type and P-type SiC epitaxial layers, a SiO2 passivation layer, and ohmic contact regions, optimized through chemical vapor deposition and thermal annealing, to reduce surface recombination and enhance the built-in potential barrier and depletion region, thereby increasing output power and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If SiC material processing technology is advanced, then surface recombination influence is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs chemical vapor deposition (CVD) to form a surface passivation layer with specific thickness and material properties. By controlling deposition parameters such as temperature, pressure, and gas flow rates, the surface recombination issue is addressed through parameter optimization rather than complex processing steps.
Solution Approach 2:
Complex mechanical or multi-step processing methods are replaced by a single-step chemical vapor deposition process. The CVD method substitutes elaborate surface treatment procedures with a straightforward chemical deposition approach, reducing manufacturing complexity while effectively passivating the surface.
2Reliability
If PN or PIN-type diode structure is used instead of Schottky diode, then built-in potential and leakage current are improved, but manufacturing difficulty increases
Solution Approach 1:
The patent combines the P-type and N-type doped regions into a single PN or PIN-type diode structure formed through sequential epitaxial growth. This merging of doping steps and regions simplifies the manufacturing process compared to forming separate Schottky contacts and doped regions, while achieving superior built-in potential and leakage current characteristics.
Solution Approach 2:
The patent uses chemically doped SiC epitaxial layers to create the PN or PIN junction, replacing the need for separate metal contacts and doped region formation. This composite approach integrates multiple functions (contact formation, doping, and junction creation) into a single epitaxial growth process, reducing manufacturing difficulty while improving device reliability.
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 configuration reduces surface recombination loss, achieves higher open circuit voltage and energy conversion efficiency, and simplifies the manufacturing process while maintaining cost-effectiveness and practicality for integration and application.
Implementation Method 1
Radioisotopic batteries are energy conversion devices that convert nuclear radiant energy into electrical energy by using a radiant volt effect which is produced in a semiconductor device by charged particles generated by radioactive isotope decay
Implementation Method 2
convert nuclear radiant energy into electrical energy by using a radiant volt effect which is produced in a semiconductor device by charged particles generated by radioactive isotope decay
Implementation Method 3
a SiO2 passivation layer, configured to cover a surface of the P-type SiC epitaxial layer
Data Source
AI summary
The present invention discloses an H-3 silicon carbide PN-type radioisotopic battery and a manufacturing method therefor. The radioisotopic battery has a structure including, from bottom to top, an N-type ohmic contact electrode, an N-type highly doped SiC substrate, an N-type SiC epitaxial layer, and a P-type SiC epitaxial layer. A P-type SiC ohmic contact doped layer is disposed on a partial upper area of the P-type SiC epitaxial layer, a P-type ohmic contact electrode is disposed on top of the P-type SiC ohmic contact doped layer, a SiO2 passivation layer is disposed on an upper area of the P-type SiC epitaxial layer where the P-type ohmic contact doped layer is removed, and an H-3 radioisotope source is provided on the top of the SiO2 passivation layer.