LED Chip Contact Grid Segmentation for Light Yield
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Solution Overview
Problem
The luminous efficiency of light-emitting diode chips is limited due to radiation absorption at electrical contacts, which affects the decoupling efficiency and light yield.
Innovation Solution
A light-emitting diode chip design with a semiconductor layer sequence and a current spreading layer, where contacts cover 1%-8% of the current spreading layer, ensuring uniform current distribution and minimizing radiation absorption. The contacts are arranged in a regular grid with a lattice constant of less than 30 μm, and a dielectric layer is used to reflect radiation back into the semiconductor layer sequence, enhancing decoupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact area is increased to improve electrical contacting and current distribution, then the electrical conductivity is improved, but the radiation absorption increases and luminous efficiency decreases
Solution Approach 1:
The contact structure is divided into multiple discrete contact points arranged in a grid pattern rather than a continuous contact layer. This segmentation allows the current to be distributed through multiple separated contact areas, reducing the total contact area coverage to 1%-8% of the current spreading layer while maintaining effective electrical contacting and current distribution.
2Loss of energy
If the contact area is decreased to reduce radiation absorption, then the luminous efficiency is improved, but the electrical conductivity and current distribution deteriorate
Solution Approach 1:
The contact structure is divided into multiple discrete contact points arranged in a grid pattern rather than a continuous contact layer. This segmentation allows the current to be distributed through multiple separated contact areas, reducing the total contact area coverage to 1%-8% of the current spreading layer while maintaining effective electrical contacting and current distribution.
Solution Approach 2:
The contact points are arranged in a two-dimensional grid pattern with specific lattice constants (less than 30 μm, preferably less than or equal to 12 μm). This spatial arrangement in multiple dimensions enables effective current spreading across the layer while keeping the total contact area minimal, resolving the contradiction between contact area and current distribution effectiveness.
3Reliability
If a current spreading layer is added to improve current distribution, then the lateral current uniformity is improved, but the device complexity increases
Solution Approach 1:
The current spreading layer serves multiple functions simultaneously: it provides lateral current distribution, supports the discrete contact points, and acts as a platform for the semiconductor layer sequence. By combining these functions into a single layer, the device complexity is minimized while achieving effective current uniformity.
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 design achieves a balanced current distribution and reduced radiation absorption, leading to increased luminous efficiency and improved thermal conductivity, optimizing the light yield and decoupling efficiency of the light-emitting diode chip.
Implementation Method 1
a dielectric layer is used to reflect radiation back into the semiconductor layer sequence, enhancing decoupling efficiency
Implementation Method 2
The charge carriers are injected into the current spreading layer via the contacts and are uniformly distributed laterally in the current spreading layer
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A light-emitting diode (LED) chip (1) is described, comprising a semiconductor layer sequence (2) that is electrically contacted by contacts (5) via a current-expansion layer (3). The contacts (5) cover between at least 1% and at most 8% of the area of the current-expansion layer (3). A free area (53), free of contacts (5), may be provided in a central region with respect to the active zone (21) of the semiconductor layer sequence (2). The contacts (5) preferably consist of separate contact points (51) arranged at the nodes of a regular grid (52) with a grid constant of less than 30 µm (e.g., equal to 12 µm). The current-expansion layer (3) preferably contains indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO) and has a thickness in the range of 15 nm to 60 nm.