Inverted Metamorphic Multijunction Solar Cell Substrate Reuse
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Solution Overview
Problem
Existing methods for manufacturing inverted metamorphic multijunction solar cells using III-V compound semiconductor materials are not adequate for producing commercially viable and energy-efficient solar cells, as they face challenges in material selection and fabrication processes.
Innovation Solution
The method involves bonding a gallium arsenide or germanium carrier with a support substrate, detaching the bulk carrier to leave a substrate, and depositing a sequence of semiconductor layers to form solar cells, including subcells with specific band gaps and lattice constants, using techniques like OMVPE or MOCVD, and reusing the sapphire substrate for cost reduction and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional manufacturing methods are used for inverted metamorphic multijunction solar cells, then the fabrication process can be simplified, but the energy conversion efficiency and commercial viability are insufficient
Solution Approach 1:
The patent inverts the conventional solar cell fabrication sequence by first forming the top subcell with the highest band gap material (GaInP2) on the substrate, then sequentially adding lower band gap subcells (GaInAs, Ge) beneath it. This inverted metamorphic structure allows each layer to be lattice-matched to the previous layer, enabling precise control of band gaps and efficiencies while maintaining fabrication feasibility through established OMVPE/MOCVD processes.
2Manufacturing precision
If higher band gap top subcells are incorporated to improve efficiency, then energy conversion efficiency increases, but material selection and fabrication complexity increase
Solution Approach 1:
The patent systematically varies the compositional parameters of the III-V semiconductor materials to achieve the desired band gap sequence. By adjusting the indium and gallium ratios in GaInP2, GaInAs, and Ge layers, the invention optimizes each subcell's band gap to match the solar spectrum while maintaining lattice matching with underlying layers, thereby achieving high efficiency without excessive fabrication complexity.
3Manufacturing precision
If III-V compound semiconductor materials are used to achieve high efficiency, then energy conversion efficiency exceeds silicon technology, but manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the solar cell into multiple discrete subcells, each with a specific band gap optimized for different portions of the solar spectrum. The top subcell (GaInP2) captures high-energy photons, the middle subcell (GaInAs) captures mid-energy photons, and the bottom Ge subcell captures low-energy photons. This segmentation allows each layer to be independently optimized and fabricated using standard OMVPE/MOCVD processes, reducing overall manufacturing complexity while achieving record efficiencies exceeding 40% under concentrated sunlight.
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 enables the production of efficient solar cells with reduced material usage and cost, allowing for the incorporation of higher band gap top subcells and reuse of substrates, enhancing energy conversion efficiency and reducing production costs.
Implementation Method 1
depositing a sequence of layers of semiconductor material forming a solar cell on the gallium arsenide substrate using techniques like OMVPE or MOCVD
Implementation Method 2
The higher conversion efficiency of III-V compound semiconductor solar cells compared to silicon solar cells is in part based on the ability to achieve spectral splitting of the incident radiation through the use of a plurality of photovoltaic regions with different band gap energies
Data Source
AI summary
A method of manufacturing a solar cell by providing a gallium arsenide carrier with a prepared bonding surface; providing a sapphire substrate; bonding the gallium arsenide carrier and the sapphire substrate to produce a composite structure; detaching the bulk of the gallium arsenide carrier from the composite structure, leaving a gallium arsenide growth substrate on the sapphire substrate; and depositing a sequence of layers of semiconductor material forming a solar cell on the growth substrate. For some solar cells, the method further includes mounting a surrogate second substrate on top of the sequence of layers of semiconductor material forming a solar cell; and removing the growth substrate.