Boron-Doped Emitter Preparation for Uniform Surface Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing boron-doped emitter preparation methods result in non-uniform boron doping concentration, leading to high surface and bulk recombination, corrosion damage, and limited recombination improvement, with the maximum doping concentration inside the silicon wafer rather than at the surface.
Innovation Solution
A method involving cleaning and texturing a silicon wafer, forming a boron-doped amorphous silicon layer, annealing to diffuse boron atoms, and removing the polycrystalline silicon layer to expose a boron-doped emitter with maximum concentration at the surface, using the amorphous silicon layer as a sacrificial layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phosphoric acid solution is used to remove boron-containing substances during the firing process, then the boron-containing substances are effectively removed, but the emitter doping concentration becomes uneven and the emitter saturation current density increases
Solution Approach 1:
The patent extracts and removes the phosphoric acid solution treatment step from the manufacturing process. By eliminating this step, the patent avoids the harmful effect of phosphoric acid causing uneven doping concentration and increased saturation current density, while still achieving reliable emitters through alternative processing methods
Solution Approach 2:
Instead of using phosphoric acid to remove boron-containing substances (conventional approach), the patent inverts the approach by avoiding phosphoric acid entirely and using alternative methods that do not compromise doping uniformity. This inversion resolves the contradiction by achieving reliability without the harmful side effects
2Reliability
If phosphoric acid is used during firing, then boron-containing substances are removed, but manufacturing cost increases due to additional process steps and quality control
Solution Approach 1:
The patent removes the phosphoric acid treatment step from the manufacturing process, thereby eliminating the associated costs of chemicals, additional processing equipment, and quality control measures. This extraction maintains emitter reliability through alternative methods while reducing overall manufacturing cost
Solution Approach 2:
The patent replaces the expensive phosphoric acid treatment process with simpler, more cost-effective processing steps that achieve the same or better results without requiring costly chemicals or extended processing time
3Reliability
If the emitter doping concentration is increased to reduce saturation current density, then emitter performance improves, but the complexity of controlling doping uniformity increases
Solution Approach 1:
The patent eliminates the phosphoric acid solution treatment step that complicates doping control. By removing this step, the patent simplifies the overall doping process while maintaining the ability to achieve low saturation current density through more straightforward doping techniques
Solution Approach 2:
The patent changes the processing parameters by avoiding phosphoric acid treatment entirely. This parameter change simplifies the doping control process while still achieving the desired emitter performance characteristics through optimized doping 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
Reduces auger and SRH recombination, minimizes corrosion damage, and enhances electrode contact, resulting in lower contact resistivity and reduced recombination difficulty.
Implementation Method 1
If a phosphoric acid solution is used to remove boron-containing substances during the firing process
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The present invention relates to the technical field of photovoltaic cells. Disclosed is a preparation method for boron-doped emitter, comprising: cleaning and texturing an n-type silicon wafer; preparing a boron-doped amorphous silicon layer on the textured surface of the front surface of the silicon wafer; carrying out annealing treatment to sequentially form a boron-doped emitter and a polycrystalline silicon layer on the front surface the silicon wafer, then cooling and introducing oxygen, so that a borosilicate glass layer is formed on the front surface of the polycrystalline silicon layer, and a silicon dioxide layer is formed on the back surface of the silicon wafer; removing the silicon dioxide layer, and polishing to form flat morphological appearance on the back surface of the silicon wafer; and removing the borosilicate glass layer and the polycrystalline silicon layer so as to expose the boron-doped emitter. The boron doping concentration of the front surface of the boron-doped emitter is not less than 95% of the maximum value of the boron doping concentration of the boron-doped emitter. According to the described method, the boron-doped amorphous silicon layer serves as a doping source and a sacrificial layer of the boron-doped emitter, resulting in a boron-doped ECV curve distinct from a traditional preparation method, thereby achieving lower surface recombination and improved contact with an interfacial metal electrode, and leading to reduced bulk recombination.