LED Current Distribution Adjustment Structure
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Solution Overview
Problem
AlGaInP-based LEDs suffer from low luminance due to current distribution issues under the p-electrode, which absorbs light emitted by the light-emitting layer, leading to inefficient luminance.
Innovation Solution
A new epitaxial structure and chip design are introduced, featuring a non-overlapping current distribution adjustment structure with a wider metal bonding layer and mirror system, preventing current flow to the epitaxial layer under the p-electrode, and optimizing the thickness ratios of etching-stop and transition layers for improved luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current flows under the p-electrode to ensure adequate current distribution, then electrical connection is improved, but light emission is reduced because the metal electrode absorbs the emitted light
Solution Approach 1:
The patent segments the current path by introducing an etching-stop layer that divides the current distribution region. This layer creates a boundary that separates the current flow path from the light emission region, allowing current to flow laterally through the layer without penetrating into the active layer beneath the p-electrode, thus maintaining both electrical connection and light emission.
Solution Approach 2:
The etching-stop layer acts as an intermediary structure between the p-electrode and the active layer. It provides a conductive path for current distribution while physically preventing current from reaching the light-emitting region, serving as a mediator that resolves the conflict between electrical connection and optical performance.
2Reliability
If the p-electrode area is increased to improve current distribution, then electrical performance is improved, but more light is absorbed by the electrode, reducing luminance
Solution Approach 1:
The patent resolves the area conflict by changing the vertical dimension through the etching-stop layer. Instead of increasing horizontal electrode area, the solution extends the current distribution function into the vertical dimension by having current flow laterally through the etching-stop layer, which has sufficient thickness to conduct current but is positioned to avoid the light emission zone.
3Illumination intensity
If the etching-stop layer thickness is increased to improve current blocking, then light emission is protected, but manufacturing complexity and material usage increase
Solution Approach 1:
The patent optimizes the etching-stop layer thickness to a specific range (0.5-2.0 μm) that provides the minimum necessary current blocking capability while minimizing material usage and structural complexity. This parameter optimization balances the competing requirements of current blocking effectiveness and manufacturing simplicity.
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 design significantly enhances luminance by ensuring current does not flow under the p-electrode, resulting in increased light emission efficiency and stability, with preferred thickness ratios and doping concentrations optimizing the LED performance.
Implementation Method 1
the portion corresponding to the p electrode position extends upwards and passes through the n-type ohmic contact layer and the first n-type transition layer, till the n-type etching-stop layer, thus forming a current distribution adjustment structure
Implementation Method 2
A new epitaxial structure and chip design are introduced, featuring a non-overlapping current distribution adjustment structure with a wider metal bonding layer and mirror system
Implementation Method 3
the first n-type transition layer is an n-type AlGaInP material layer, with doping concentration of at least 7E17 and preferred value of 1E18, and the doping material can be Si, Te
Data Source
AI summary
A light-emitting diode includes: an epitaxial-laminated layer having from bottom up: an n-type ohmic contact layer, a first n-type transition layer, an n-type etching-stop layer, a second n-type transition layer, an n-type confinement layer, an active layer, a p-type confinement layer, a p-type transition layer and a p-type window layer; a p electrode on the upper surface of the p-type window layer; a metal bonding layer over the bottom surface of the n-type ohmic contact layer, wherein, the portion corresponding to the p electrode position extends upwards and passes through the n-type ohmic contact layer and the first n-type transition layer, till the n-type etching-stop layer, thereby forming a current distribution adjustment structure such that the injected current would not flow towards the epitaxial-laminated layer right below the p electrode; and a conductive substrate over the bottom surface of the metal bonding layer.