Germanium-Doped Czochralski Silicon Substrate for Solar Cells
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Solution Overview
Problem
Conventional single-crystal silicon substrates for solar cells have limited conversion efficiency, leading to high production costs, and the use of germanium as a doping agent in these substrates has not been fully explored to enhance performance.
Innovation Solution
A solar-cell single-crystal silicon substrate with a germanium content of not less than 0.1 mole % and less than 1.0 mole %, produced using the Czochralski method, where the germanium is homogeneously distributed to enhance conversion efficiency by interacting with doping agents, thereby reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional single-crystal silicon substrates are used for solar cells, then production costs are reduced through established manufacturing processes, but conversion efficiency is limited and cannot reach the levels of compound semiconductor solar cells
Solution Approach 1:
The patent changes the chemical composition parameter by introducing germanium as a doping agent in specific concentrations (0.1-1.0 mole %) to modify the electrical and optical properties of single-crystal silicon, thereby improving conversion efficiency while maintaining compatibility with existing CZ manufacturing processes
Solution Approach 2:
The patent creates a composite material system by combining silicon with germanium dopants, forming a Si-Ge composite single-crystal structure that leverages the beneficial properties of both elements to achieve higher conversion efficiency than pure silicon while remaining manufacturable through established processes
2Loss of energy
If germanium is added as a doping agent to single-crystal silicon substrates, then conversion efficiency is significantly improved, but the production cost increases due to additional doping processes and material costs
Solution Approach 1:
The patent optimizes the germanium concentration parameter within a specific range (0.1-1.0 mole %) to achieve the desired conversion efficiency improvement while minimizing the quantity of germanium material required, thereby controlling production costs
Solution Approach 2:
The patent applies partial doping with germanium rather than complete substitution, using just enough germanium (0.1-1.0 mole %) to achieve significant efficiency improvement without the full cost implications of complete germanium-based structures
3Loss of energy
If high-purity silicon is used to obtain higher conversion efficiency, then the substrate quality is improved, but the production cost increases due to extensive purification processes
Solution Approach 1:
The patent changes the purity parameter by introducing controlled amounts of germanium as a deliberate dopant, which improves conversion efficiency through enhanced electrical properties without requiring the extreme purification levels that would be needed for intrinsic high-performance silicon
Solution Approach 2:
The germanium dopant provides self-service by simultaneously improving conversion efficiency and enabling the use of slightly less purified silicon, as the germanium atoms compensate for residual impurities through their beneficial effects on carrier lifetime and electrical conductivity
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
The enhanced germanium content in the substrate significantly improves conversion efficiency, making the solar cell more cost-effective and increasing its power generation capabilities compared to conventional single-crystal silicon substrates.
Implementation Method 1
The single-crystal silicon which is utilized for a substrate material of the semiconductor integrated circuit is produced by the CZ method in which the single-crystal silicon is directly grown by pulling the single-crystal silicon from molten silicon
Data Source
AI summary
In growing a single-crystal silicon by the present invention in a Czochralski method, after a surface of a silicon melt is brought into contact with a seed crystal in a crucible, the silicon melt being added with germanium, the single-crystal silicon is pulled while rotated, and the solar-cell single-crystal silicon substrate is sliced from the single-crystal silicon containing germanium, whereby a germanium content of solar-cell single-crystal silicon substrate is set in the range of not less than 0.03 mole % to less than 1.0 mole % when resistivity ranges from 1.4 to 1.9 Ωcm. Therefore, conversion efficiency is enhanced when compared with conventional single-crystal silicon substrates. Accordingly, solar cell power generation costs decreases, so that the single-crystal silicon of the present invention can widely be utilized as the substrate for the solar cell in which the high conversion efficiency is increasingly demanded.