Compound Semiconductor Solar Cell Copper Electrode Cost Reduction
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Solution Overview
Problem
The high cost of gold (Au) used in forming electrode metal layers for compound semiconductor solar cells makes it difficult to lower manufacturing costs, and using copper (Cu) leads to etching and degradation of the semiconductor layer due to copper plating solutions.
Innovation Solution
A method involving the formation of a seed metal layer and a second mask layer to protect the semiconductor layer during copper plating, where the seed metal layer is used to pattern the front contact layer before forming the electrode metal layer, ensuring the copper layer is formed with a width that covers both ends of the seed metal layer, preventing etching and degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gold (Au) is used for the electrode metal layer, then corrosion resistance and reliability are improved, but manufacturing cost increases significantly
Solution Approach 1:
The electrode metal layer is segmented into two distinct layers: a seed metal layer (5-50 nm thick) made of corrosion-resistant materials like Au, Ag, or Cu, and a bulk metal layer (1-30 μm thick) made of inexpensive Cu or Al. This segmentation allows the expensive corrosion-resistant material to be used only where necessary for reliability, while the bulk of the electrode uses cheap material, resolving the contradiction between reliability and manufacturing cost.
Solution Approach 2:
Different regions of the electrode structure are assigned different material qualities: the surface layer (seed metal) has high corrosion resistance for reliability, while the underlying bulk layer (electrode metal) has low cost for manufacturing efficiency. This local differentiation of material properties allows simultaneous optimization of both reliability and cost.
2Ease of manufacture
If copper (Cu) is used for the electrode metal layer, then manufacturing cost is reduced, but the compound semiconductor layer is etched and dissolved by copper plating solution
Solution Approach 1:
The seed metal layer is formed on the compound semiconductor layer before the bulk copper electrode metal layer is deposited. This preliminary layer acts as a protective barrier that prevents the copper plating solution from contacting and damaging the semiconductor layer during the copper deposition process, thereby enabling cost reduction without causing harmful effects.
Solution Approach 2:
The seed metal layer serves as an intermediary between the compound semiconductor layer and the copper electrode metal layer. It mediates the interaction by blocking the harmful copper plating solution from the semiconductor while allowing electrical conductivity to be established, thus enabling the use of inexpensive copper without causing etching or dissolution.
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 allows for the use of cheaper copper materials while preventing damage and degradation of the compound semiconductor layer, maintaining performance and reducing manufacturing costs.
Implementation Method 1
The seed metal layer may be formed by depositing any one material selected from the group consisting of palladium (Pd), nickel (Ni), titanium (Ti), platinum (Pt), and silver (Ag) or an alloy thereof to a thickness of 5 nm to 100 nm by physical vapor deposition.
Implementation Method 2
forming an electrode metal layer on the seed metal layer not covered by the second mask layer
Data Source
AI summary
A compound semiconductor solar cell and a method of manufacturing the same are disclosed. The method for fabricating a compound semiconductor solar cell comprises forming a first mask layer on a front surface of a compound semiconductor layer of a second region which is a region other than a first region where the front electrode is to be formed; forming a seed metal layer on the front surface of the compound semiconductor layer of the first region and on the first mask layer of the second region; removing the seed metal layer over the first mask layer and the first mask layer; removing a part of the compound semiconductor layer of the second region from the front surface of the compound semiconductor layer by using the seed metal layer of the first region as a mask; forming a second mask layer on the compound semiconductor layer of the second region; forming an electrode metal layer on the seed metal layer not covered by the second mask layer; and removing the second mask layer.