Microwave Crystallization of Amorphous Silicon Solar Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Amorphous silicon thin film solar cells have low energy-converting efficiency and suffer from the Staebler-Wronski effect, where efficiency decreases over time, and microcrystalline silicon layers formed under higher process pressures or with higher frequency plasma sources face contamination and thickness uniformity issues, leading to reduced productivity.
Innovation Solution
A method of fabricating solar cells using a microwave to crystallize intrinsic semiconductor layers from amorphous silicon to microcrystalline silicon, improving crystallinity and deposition rate while minimizing process time and contamination, employing a microwave generating unit that moves over the substrate to apply microwaves within specific frequency ranges and controlled conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon is used for thin film solar cells, then material cost is reduced and flexibility is improved, but energy-converting efficiency is lowered
Solution Approach 1:
The patent changes the crystalline structure parameter of the silicon material from amorphous to microcrystalline, thereby improving energy-converting efficiency while maintaining the thin film structure advantages of low cost and flexibility
Solution Approach 2:
The patent uses a composite structure combining microcrystalline silicon intrinsic layer with amorphous silicon buffer and contact layers, optimizing both efficiency and manufacturing advantages
2Duration of action of stationary object
If amorphous silicon thin film solar cells are exposed to light for longer time, then operational duration increases, but efficiency is reduced due to Staebler-Wronski effect
Solution Approach 1:
The patent changes the material structure from amorphous to microcrystalline silicon, which fundamentally eliminates the Staebler-Wronski effect and maintains stable efficiency over extended operational periods
3Productivity
If microcrystalline silicon is deposited under higher process pressure to increase deposition rate, then productivity is improved, but contamination increases and layer density is reduced
Solution Approach 1:
The patent optimizes the deposition pressure parameter to an intermediate range that balances deposition rate with layer quality, avoiding both low-pressure slow deposition and high-pressure contamination
Solution Approach 2:
The patent implements process monitoring and control mechanisms to maintain optimal deposition conditions, adjusting parameters in real-time to prevent contamination while maintaining high deposition rates
4Productivity
If higher frequency plasma source is used to deposit microcrystalline silicon, then deposition rate is improved, but thickness uniformity is degraded due to standing wave
Solution Approach 1:
The patent introduces motion dynamics by moving the substrate or plasma source during deposition, disrupting standing wave patterns and achieving uniform thickness distribution while maintaining high deposition rates
Solution Approach 2:
The patent employs periodic modulation of deposition parameters or oscillatory motion to prevent standing wave formation, ensuring uniform layer thickness throughout the substrate
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 enhances the productivity of solar cell fabrication by forming high-crystallinity microcrystalline silicon layers with improved efficiency and reduced process time, addressing the limitations of amorphous silicon and microcrystalline silicon deposition methods, and is applicable to tandem or triple structure solar cells.
Implementation Method 1
irradiating a microwave to form a second intrinsic semiconductor layer of microcrystalline silicon by crystallizing the first intrinsic semiconductor layer
Implementation Method 2
crystallizing the first intrinsic semiconductor layer
Implementation Method 3
irradiating a first microwave to form a second intrinsic semiconductor layer of microcrystalline silicon by crystallizing the first intrinsic semiconductor layer
Data Source
AI summary
A method of fabricating a solar cell includes: forming a first electrode on a substrate; forming a first impurity-doped semiconductor layer on the first electrode; forming a first intrinsic semiconductor layer of amorphous silicon on the first impurity-doped semiconductor layer; forming a second impurity-doped semiconductor layer over the first impurity-doped semiconductor layer, forming a second electrode over the second impurity-doped semiconductor layer; and irradiating a first microwave to form a second intrinsic semiconductor layer of microcrystalline silicon by crystallizing the first intrinsic semiconductor layer.