Distributed Current Blocking Structures for LED Uniformity
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Solution Overview
Problem
Conventional semiconductor light emitting diodes (LEDs) suffer from non-uniform light generation and potential damage due to high current density concentrations under opaque electrodes, leading to inefficiencies and reliability issues.
Innovation Solution
The implementation of a strip-shaped electrode with distributed current blocking structures, formed by etching or damaging selected portions of the p++GaN layer, creates relatively high resistive areas that impede current flow under the electrode, ensuring uniform current distribution and light generation across the active layer, except under opaque electrodes where current flow is blocked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a current blocking layer is positioned below the top electrode to prevent light emission under the electrode, then luminous efficiency is improved, but current density becomes concentrated at the edge of the current blocking layer causing non-uniform light generation and potential device damage
Solution Approach 1:
The current blocking layer is segmented into multiple discrete current blocking structures (first current blocking structure directly under the electrode and second current blocking structures in the outer region) rather than a single continuous layer. This segmentation distributes the current blocking function across multiple elements, preventing current concentration at a single edge while maintaining effective light blocking where needed.
Solution Approach 2:
Different regions of the LED have different current blocking characteristics: the first current blocking structure provides strong blocking directly under the electrode to prevent light emission, while the second current blocking structures in the outer region provide distributed blocking to guide current flow uniformly across the active layer without creating concentration points.
2Productivity
If current blocking structures are used to improve light emission performance, then luminous efficiency increases, but the current flow becomes non-uniform leading to local heating and potential damage
Solution Approach 1:
The current blocking function is divided into multiple discrete structures rather than a single continuous barrier. The first current blocking structure under the electrode and the second current blocking structures in the outer region work together to distribute current flow, preventing localized heating while maintaining high light emission performance in the active regions.
Solution Approach 2:
The second current blocking structures act as intermediary elements between the first current blocking structure and the peripheral regions. These structures guide current flow in a distributed manner, preventing direct current concentration at the edges while ensuring uniform current distribution across the light-emitting active 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
This approach results in substantially uniform light generation and reduced risk of damage from current concentration, enhancing the luminous efficiency and reliability of LED devices.
Implementation Method 1
The implementation of a strip-shaped electrode with distributed current blocking structures, formed by etching or damaging selected portions of the p++GaN layer, creates relatively high resistive areas that impede current flow under the electrode
Implementation Method 2
Light is emitted from an active layer of semiconductor materials sandwiched between oppositely doped layers when a voltage is applied across the doped layers
Data Source
AI summary
An LED device includes a strip-shaped electrode, a strip-shaped current blocking structure and a plurality of distributed current blocking structures. The current blocking structures are formed of an insulating material such as silicon dioxide. The strip-shaped current blocking structure is located directly underneath the strip-shaped electrode. The plurality of current blocking structures may be disc shaped portions disposed in rows adjacent the strip-shaped current blocking structure. Distribution of the current blocking structures is such that current is prevented from concentrating in regions immediately adjacent the electrode, thereby facilitating uniform current flow into the active layer and facilitating uniform light generation in areas not underneath the electrode. In another aspect, current blocking structures are created by damaging regions of a p-GaN layer to form resistive regions. In yet another aspect, current blocking structures are created by etching away highly doped contact regions to form regions of resistive contact between conductive layers.