Multilayer Metallization for Solar Cell Adhesion
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Solution Overview
Problem
Existing metallization methods for solar cells face challenges in achieving reliable and long-lasting adhesion of metal layers to both dielectric and semiconductor materials, particularly with precious metals like silver, palladium, or gold showing insufficient adhesion to dielectrics.
Innovation Solution
A multilayer metallization system comprising a gold-germanium layer, a titanium layer, and a palladium or nickel/platinum layer, with a silver layer, which is heat-treated to achieve a eutectic connection between the titanium and dielectric layers, ensuring reliable bonding to both dielectric and semiconductor surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple metal layers are added to achieve reliable adhesion to both dielectric and semiconductor, then adhesion reliability is improved, but device complexity increases
Solution Approach 1:
The first metal layer serves multiple functions: it adheres to the semiconductor layer, provides an adhesion surface for the second metal layer, and can serve as part of the electrical contact structure. This multi-functionality reduces the need for additional separate layers, achieving reliable adhesion to both dielectric and semiconductor while limiting the increase in device complexity.
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 multilayer system provides a cost-effective and efficient solution with improved adhesion and bonding capabilities, reducing the need for additional process steps and metal structures, and enabling optimized manufacturing and design of through-contacts in multi-junction solar cells.
Implementation Method 1
heat-treated to achieve a eutectic connection between the titanium and dielectric layers
Implementation Method 2
a first layer, comprising gold and germanium, with a layer thickness D1 of at least 2 nm and at most 50 nm
Data Source
AI summary
A stacked multi-junction solar cell with a metallization comprising a multilayer system, wherein the multi-junction solar cell has a germanium substrate forming a bottom side of the multi-junction solar cell, a germanium subcell, and at least two III-V subcells, the multilayer system of the metallization has a first layer, comprising gold and germanium, a second layer comprising titanium, a third layer, comprising palladium or nickel or platinum, with a layer thickness, and at least one metallic fourth layer, and the multilayer system of the metallization covers at least one first and second surface section and is integrally connected to the first and second surface section, wherein the first surface section is formed by the dielectric insulation layer and the second surface section is formed by the germanium substrate or by a III-V layer.