Amorphous Silicon Trap Layer for Hydrogen Diffusion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solar cells with amorphous silicon layers formed by plasma CVD method deteriorate at high temperatures due to hydrogen diffusion, leading to reduced output characteristics, particularly affecting the activation rate of boron dopant and built-in electric field.
Innovation Solution
A photovoltaic device with a hydrogen-diffusion reducing area between the doped and intrinsic amorphous semiconductor thin-films, formed by varying hydrogen concentrations and impurity doping, reduces hydrogen diffusion from the intrinsic to the doped amorphous silicon layers, thereby minimizing output characteristic deterioration during heating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high-temperature processing is performed for electrode formation and lamination coating, then these manufacturing steps can be completed, but hydrogen diffusion occurs from the intrinsic amorphous silicon layer to the doped amorphous silicon layer, reducing the activation rate of boron dopant and deteriorating output characteristics
Solution Approach 1:
An undoped amorphous silicon layer is introduced as an intermediary barrier layer between the intrinsic amorphous silicon layer and the doped amorphous silicon layer. This intermediate layer prevents direct hydrogen diffusion from the intrinsic layer to the doped layer during high-temperature processing, thereby protecting the boron dopant activation rate while allowing electrode formation and lamination coating to proceed
Solution Approach 2:
The amorphous silicon structure is segmented into three distinct layers: an intrinsic amorphous silicon layer, an undoped amorphous silicon layer, and a doped amorphous silicon layer. This segmentation creates a buffer zone that isolates the doped layer from hydrogen diffusion sources, enabling high-temperature manufacturing steps without compromising output characteristics
2Manufacturing precision
If the hydrogen concentration in the intrinsic amorphous silicon layer is increased to improve interfacial quality, then interfacial quality improves, but hydrogen diffusion to the doped layer increases, reducing the activation rate of boron dopant
Solution Approach 1:
The undoped amorphous silicon layer serves as a mediator that decouples the relationship between hydrogen concentration in the intrinsic layer and dopant activation in the doped layer. This allows the intrinsic layer to maintain high hydrogen concentration for improved interfacial quality while the undoped layer blocks hydrogen from reaching the doped layer, preserving boron dopant activation rate
Solution Approach 2:
Different regions of the amorphous silicon structure are assigned different hydrogen concentrations and doping levels optimized for their specific functions: the intrinsic layer has high hydrogen concentration for interfacial quality, the undoped layer has moderate hydrogen concentration as a diffusion barrier, and the doped layer has controlled hydrogen concentration to maintain dopant activation
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
The implementation of a hydrogen-diffusion reducing area effectively reduces hydrogen diffusion, preserving the output characteristics of solar cells even after high-temperature processing, allowing for the use of materials requiring high-temperature electrode formation without significant performance loss.
Implementation Method 1
formed by a plasma CVD method
Implementation Method 2
diffusion of hydrogen; the diffusion of hydrogen from an i-type amorphous silicon layer to a p-type amorphous silicon layer
Data Source
AI summary
In the photovoltaic devices comprising a substantially intrinsic amorphous silicon layer containing hydrogen between an n-type single-crystal silicon substrate and a p-type amorphous silicon layer containing hydrogen, the photovoltaic device according to the present invention comprises a trap layer that contains less hydrogen than the intrinsic amorphous silicon layer between the p-type amorphous silicon layer and the intrinsic amorphous silicon layer. The trap layer reduces hydrogen diffusion from the intrinsic amorphous silicon layer to the p-type amorphous silicon layer.