Solar Cell Emitter Region Doping via Local Quality
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Solution Overview
Problem
Current solar cell manufacturing methods face challenges in optimizing doping concentrations and crystallinity across the emitter region, leading to inefficiencies in carrier recombination and contact resistance, which affect the solar cell's performance and manufacturing time.
Innovation Solution
A method involving sequential layer formation, thermal processing, and electrode formation, where a tunnel layer, intrinsic amorphous silicon layer, and dopant layer are formed on a semiconductor substrate, followed by recrystallization and activation processes to create a polycrystalline silicon emitter region with varying doping concentrations and crystallinity, improving carrier recombination and contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used to form the emitter region, then the doping process can be completed, but the doping concentration cannot be uniformly optimized across different portions of the emitter region, leading to inefficient carrier recombination and increased contact resistance
Solution Approach 1:
The patent applies local quality by forming a dopant layer with spatially varying thickness across the emitter region. The dopant layer thickness is greater in the first portion (contacting the electrode) and smaller in the second portion (contacting the tunnel layer), enabling different doping concentrations in different regions. This resolves the contradiction by allowing optimized carrier recombination in one region while maintaining appropriate contact properties in another region, achieving both high reliability and manufacturing precision.
2Reliability
If multiple thermal processing steps are used to form the emitter region and activate dopants, then the doping can be activated, but the manufacturing time increases
Solution Approach 1:
The patent merges the dopant activation function into the existing thermal processing step used for emitter region formation. The thermal processing operation simultaneously activates the dopant in the dopant layer and forms the emitter region, eliminating the need for separate dopant activation steps. This resolves the contradiction by achieving reliable dopant activation while minimizing manufacturing time through process integration.
3Reliability
If the emitter region is formed with high doping concentration throughout, then contact resistance is reduced, but carrier recombination efficiency decreases due to impurity effects
Solution Approach 1:
The patent applies local quality by creating spatially varying doping concentrations in the emitter region. The first portion (contacting the electrode) has higher doping concentration to reduce contact resistance, while the second portion (contacting the tunnel layer) has lower doping concentration to minimize carrier recombination losses. This resolves the contradiction by optimizing each region's doping level for its specific function, achieving both low contact resistance and high carrier recombination efficiency.
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 reduces carrier recombination, enhances contact resistance, and simplifies the manufacturing process by simultaneously forming the front surface field and emitter regions through a single thermal process, leading to improved solar cell efficiency and reduced manufacturing time.
Implementation Method 1
forming an emitter region by recrystallizing the intrinsic amorphous silicon layer into an intrinsic polycrystalline silicon layer
Implementation Method 2
diffusing and activating the impurities of the second conductive type of the dopant layer into the recrystallized intrinsic polycrystalline silicon layer
Implementation Method 3
sequentially forming a tunnel layer, an intrinsic amorphous silicon layer, and a dopant layer on a back surface of a semiconductor substrate
Data Source
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AI summary
A solar cell and a method for manufacturing the same are disclosed. The solar cell includes a semiconductor substrate containing impurities of a first conductive type, a tunnel layer positioned on the semiconductor substrate, an emitter region positioned on the tunnel layer and containing impurities of a second conductive type opposite the first conductive type, a dopant layer positioned on the emitter region and formed of a dielectric material containing impurities of the second conductive type, a first electrode connected to the semiconductor substrate, and a second electrode configured to pass through the dopant layer and connected to the emitter region.