Metal Oxide Interface Layer for Copper Silicon Solar Cells
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Solution Overview
Problem
Existing silicon solar cells face challenges with interdiffusion between copper wiring and silicon substrates, leading to poor adhesion and ohmic contact characteristics, which affect long-term reliability and efficiency.
Innovation Solution
A metal oxide layer comprising titanium or manganese, combined with vanadium, niobium, tantalum, silicon, copper, or nickel, is formed between the copper wiring and the silicon substrate to act as a diffusion barrier and enhance adhesion, while an antireflection film is used to minimize carrier recombination and reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper is used to substitute silver for collector electrode wiring, then material cost is reduced, but interdiffusion between copper and silicon occurs leading to deteriorated solar cell properties
Solution Approach 1:
A metal oxide layer comprising titanium or manganese is introduced as an intermediary diffusion barrier between copper wiring and silicon substrate. This intermediate layer prevents direct interdiffusion while maintaining electrical conductivity, thus preserving solar cell properties while enabling copper substitution for silver.
2Reliability
If a diffusion barrier layer is introduced between copper and silicon, then interdiffusion is minimized, but electrical contact resistance increases due to Schottky contact characteristics
Solution Approach 1:
The metal oxide layer changes the electrical parameters at the copper-silicon interface by providing ohmic contact characteristics. Through controlled composition and thickness of the titanium or manganese oxide layer, the contact resistance is optimized to be low while maintaining diffusion barrier functionality.
3Object-affected harmful factors
If impurity concentration in silicon contact region is increased to reduce resistance, then electrical contact characteristics improve, but diffusion into silicon occurs through the interface layer
Solution Approach 1:
The metal oxide layer serves as a protective intermediary that prevents impurity diffusion into silicon while maintaining low contact resistance. The layer blocks diffusion pathways at the interface without requiring high impurity concentration in the silicon contact region.
4Device complexity
If copper wiring is directly formed on silicon substrate, then manufacturing process is simplified, but adhesion between copper and silicon is insufficient
Solution Approach 1:
The metal oxide layer acts as an adhesion promoter and intermediary between copper wiring and silicon substrate. It provides chemical bonding sites that enhance adhesion strength while maintaining a simple manufacturing process through direct formation on the silicon surface.
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 solution effectively reduces interdiffusion, improves adhesion and ohmic contact characteristics, enhances conversion efficiency, and minimizes carrier recombination, leading to improved long-term reliability and cost-effectiveness of silicon solar cells.
Implementation Method 1
a diffusion barrier layer is required between copper and silicon in order to minimize interdiffusion of copper and silicon
Implementation Method 2
the electrical contact characteristics at the interface are of ohmic contacts
Implementation Method 3
an antireflection film is used to minimize carrier recombination and reflectivity
Data Source
AI summary
The present invention is provided with an interface layer that minimizes interdiffusion between a silicon substrate and copper electrode wiring that are used as a solar cell, that improves the adhesive properties of copper wiring, and that is used to obtain ohmic contact characteristics. This silicon solar cell comprises a silicon substrate and is provided with a metal oxide layer that is formed on the silicon substrate and wiring that is formed on the metal oxide layer and that comprises mainly copper. The metal oxide layer contains (a) one of either titanium or manganese, (b) one of vanadium, niobium, tantalum, or silicon, and (c) at least one of copper and nickel. In addition, the metal oxide layer comprises copper or nickel as metal particles that are diffused in the interior of the metal oxide layer.