Gradient Current Spreading Layer for LED Transmittance
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Solution Overview
Problem
Existing optoelectronic semiconductor components face challenges in achieving electrically and mechanically stable contacts, which are crucial for efficient current distribution and radiation transmission.
Innovation Solution
A semiconductor component with a current spreading layer made of transparent, conductive metal oxide, where the metal concentration decreases from the semiconductor body interface to the outer surface, ensuring a strong ohmic contact and high transmittance for electromagnetic radiation, is developed. This layer is produced by applying a thin metal layer and its oxide, followed by thermal treatment to create a gradient in metal concentration, enhancing adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current spreading layer with high metal concentration is applied to the semiconductor body, then electrical conductivity and adhesion are improved, but transmittance of electromagnetic radiation deteriorates
Solution Approach 1:
The patent applies a non-uniform metal concentration distribution within the current spreading layer. The metal concentration is highest at the interface with the semiconductor body (providing excellent adhesion and electrical contact) and gradually decreases toward the outer surface (maintaining optical transmittance). This spatial variation in material composition allows different regions of the same layer to fulfill different functions: the metal-rich region ensures electrical stability while the metal-poor region ensures optical transparency.
Solution Approach 2:
The patent changes the concentration parameter of metal atoms within the current spreading layer. By controlling the metal concentration to decrease from the semiconductor body interface toward the outer surface, the layer achieves optimal balance between electrical conductivity (requiring high metal content) and optical transmittance (requiring low metal content). This parameter gradient enables simultaneous satisfaction of conflicting electrical and optical requirements.
2Illumination intensity
If a transparent conductive metal oxide layer is applied, then transmittance is improved, but electrical conductivity and adhesion deteriorate
Solution Approach 1:
The patent creates a functionally differentiated structure within the current spreading layer by implementing local quality variations. The region adjacent to the semiconductor body has high metal concentration for excellent electrical contact and adhesion, while the outer region has low metal concentration for high optical transmittance. This local differentiation allows the single layer to simultaneously provide both electrical and optical functions that would otherwise require separate layers.
Solution Approach 2:
The current spreading layer is constructed as a composite material system containing metal atoms distributed within an oxide matrix. The varying metal concentration creates a composite structure where metal-rich regions provide electrical conductivity and adhesion, while metal-poor regions provide optical transparency. This composite approach allows optimization of multiple properties within a single integrated layer.
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 provides a stable and efficient current distribution with high electrical conductivity and reduced risk of delamination, while maintaining high transmittance for electromagnetic radiation, thus improving the performance of optoelectronic components like photodiodes and light-emitting diodes.
Implementation Method 1
the current spreading layer is suitable for distributing a current impressed in a limited area of the current spreading layer over the largest possible area
Implementation Method 2
The current spreading layer is preferably additionally permeable to at least part of the electromagnetic radiation generated in the optoelectronic semiconductor chip or received by the optoelectronic semiconductor chip. The transmittance of the current spreading layer is preferably at least 90 percent for electromagnetic radiation in the visible spectral range.
Implementation Method 3
the current spreading layer contains a metal which forms a transparent, electrically conductive metal oxide in the current spreading layer
Implementation Method 4
This layer is produced by applying a thin metal layer and its oxide, followed by thermal treatment to create a gradient in metal concentration, enhancing adhesion and conductivity.
Data Source
Figure 1A~1C
Figure 2~3
AI summary
An optoelectronic semiconductor component with a semiconductor body (10) and a current spreading layer (3) is disclosed. The current spreading layer (3) is applied at least on parts of the semiconductor body (10). The current spreading layer (3) contains a metal (1) that forms a transparent, electroconductive metal oxide (2) in the current spreading layer, and the concentration (x) of the metal (1) decreases from the side of the current spreading layer (3) facing the semiconductor body (10) to the side of the current spreading layer (3) away from the semiconductor body (10). Also disclosed is a method for producing this type of semiconductor component.