Crystalline Silicon Solar Cell Interface Passivation
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Solution Overview
Problem
Existing methods for enhancing photoelectric conversion characteristics in crystalline silicon-based solar cells, such as hydrogen plasma treatment and chemical annealing, face challenges in reducing defects at the interface between the single-crystal silicon substrate and the silicon-based thin-film layer, leading to inadequate enhancement of conversion efficiency and poor productivity.
Innovation Solution
A method involving the formation of an intrinsic amorphous silicon-based layer with a first thin-film layer of 1-10 nm thickness, followed by hydrogen plasma treatment, and subsequent deposition of a second thin-film layer, with controlled hydrogen content and plasma treatment conditions to minimize plasma damage and enhance passivation effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen plasma treatment is applied to clean the crystalline silicon substrate surface before forming the intrinsic amorphous silicon-based layer, then the substrate surface is cleaned and passivation is enhanced, but plasma damage occurs at the interface leading to increased defects
Solution Approach 1:
A first intrinsic amorphous silicon-based thin-film layer is formed on the crystalline silicon substrate surface before the hydrogen plasma treatment. This preliminary layer protects the substrate from plasma damage while still allowing hydrogen to pass through and passivate the substrate surface. The thin-film layer is then removed after plasma treatment, leaving a clean interface without plasma-induced defects.
Solution Approach 2:
The first intrinsic amorphous silicon-based thin-film layer acts as an intermediary between the hydrogen plasma and the crystalline silicon substrate. It mediates the plasma treatment by allowing hydrogen atoms to pass through for passivation while blocking direct plasma exposure that would cause damage to the substrate surface.
2Productivity
If the intrinsic amorphous silicon-based layer is formed in a single step, then the process is simple and productive, but defects at the interface between the substrate and the layer are not sufficiently reduced
Solution Approach 1:
The formation of the intrinsic amorphous silicon-based layer is segmented into multiple steps: first forming a thin-film layer, then performing hydrogen plasma treatment, and finally forming the remaining layer. This segmentation allows the plasma treatment to occur at the optimal moment for passivation while minimizing plasma damage, thereby improving interface quality without significantly compromising productivity.
Solution Approach 2:
The first intrinsic amorphous silicon-based thin-film layer is formed as a preliminary step before the hydrogen plasma treatment. This preliminary action prepares the surface for optimal plasma interaction, enabling effective passivation and defect reduction while maintaining a streamlined manufacturing process.
3Reliability
If chemical annealing is performed by repeatedly depositing and plasma-treating the amorphous silicon-based thin-film, then defects in the layer are reduced, but the process complexity and time increase significantly
Solution Approach 1:
The hydrogen plasma treatment step is extracted and performed separately after the first thin-film layer is formed, rather than repeatedly alternating deposition and plasma treatment. This extraction achieves the necessary passivation and defect reduction in a single plasma treatment step, significantly reducing process time while maintaining film quality.
Solution Approach 2:
The first intrinsic amorphous silicon-based thin-film layer is formed as a preliminary structure that enables effective hydrogen plasma treatment. This preliminary layer allows the plasma treatment to be performed once rather than repeatedly, achieving the same defect reduction effect with less processing time.
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 effectively reduces defects at the interface, improving the photoelectric conversion efficiency and productivity by enhancing the passivation effect on the single-crystal silicon substrate, resulting in a crystalline silicon-based photoelectric conversion device with improved open circuit voltage and carrier lifetime.
Implementation Method 1
the crystalline silicon substrate surface is subjected to a hydrogen plasma treatment to clean the substrate surface
Implementation Method 2
defects present on the surface of single-crystal silicon (principally dangling bonds of silicon) can be terminated (passivated) with hydrogen
Implementation Method 3
due to a presence of an intrinsic amorphous silicon thin-film, carrier-introduction impurities can be prevented from diffusing to the surface of single-crystal silicon
Implementation Method 4
multi-layer plasma-enhanced chemical vapour deposition techniques involving the deposition of individual a-Si:H sub-layers
Data Source
AI summary
Disclosed is a method for manufacturing a crystal silicon-based photoelectric conversion device. A crystalline-based silicon photoelectric conversion device of the present invention comprises: an intrinsic silicon-based layer of a first conductivity type layer-side and a silicon-based layer of a first conductivity type, in this order on one surface of a single-crystal silicon substrate of the first conductivity type; and an intrinsic silicon-based layer of an opposite conductivity type layer-side and a silicon-based layer of an opposite conductivity type, in this order on the other surface of the single-crystal silicon substrate of the first conductivity type. At least one of a step of forming the intrinsic silicon-based layer of first conductivity type layer-side and a step of forming the intrinsic silicon-based layer of opposite conductivity type layer-side includes the sub-steps in the following order: a step of forming a first intrinsic silicon-based thin-film layer having a thickness of 1 nm to 10 nm on the single-crystal silicon substrate of the first conductivity type by a plasma-enhanced CVD method; a step of plasma-treating the single-crystal silicon substrate of the first conductivity type, on which the first intrinsic silicon-based thin-film layer is formed thereon, in an atmosphere of a gas containing hydrogen as a main component; and a step of forming a second intrinsic silicon-based thin-film layer on the first intrinsic silicon-based thin-film layer by a plasma-enhanced CVD method.