SSL Contact Structure for Uniform Current Density in MQW LEDs
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Solution Overview
Problem
Conventional SSL devices exhibit spatially non-uniform current densities across different regions of the GaN/InGaN MQWs, leading to reduced overall operating efficiency.
Innovation Solution
The SSL device incorporates a second contact with a conductive material and an insulative material, where the contact portions are configured to modulate local current densities by adjusting their shape, size, and configuration, thereby influencing the contact resistance and achieving balanced current density profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional contacts with uniform structure are used, then the device structure is simple, but the current density becomes spatially non-uniform leading to reduced operating efficiency
Solution Approach 1:
The contact structure is designed with spatially varying properties: the second contact includes an insulative material layer with different thicknesses in different regions, and conductive material portions with varying shapes and sizes. This local variation in contact structure creates region-specific contact resistances that compensate for the non-uniform current density distribution in the GaN/InGaN MQWs, ensuring more uniform current flow across all regions and improving overall operating efficiency.
2Manufacturing precision
If the contact structure is modified to balance current densities, then the current uniformity improves, but the manufacturing process becomes more complex
Solution Approach 1:
The second contact is segmented into multiple functional layers: an insulative material layer with spatially varying thickness and multiple conductive material portions with different shapes and sizes. This segmentation allows independent optimization of each layer's properties to achieve the desired current density distribution. The segmented structure enables precise control over contact resistance in different regions while maintaining a systematic fabrication approach that builds layers sequentially.
3Reliability
If contact portions are optimized for uniform current density, then regional current balance improves, but the contact design complexity increases
Solution Approach 1:
The contact structure utilizes systematic variations in key parameters: the insulative material layer thickness is varied across different regions, and the conductive material portions are designed with different shapes, sizes, and positions. These parameter changes are strategically implemented to create the desired spatial distribution of contact resistance. By controlling these parameters during fabrication, the design achieves reliable and consistent current flow across all regions of the device.
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 configuration results in more balanced and uniform current density profiles across the SSL device, enhancing its operating efficiency by ensuring consistent current flow through different regions.
Implementation Method 1
the contact portions are configured to modulate local current densities by adjusting their shape, size, and configuration, thereby influencing the contact resistance and achieving balanced current density profiles
Data Source
AI summary
Solid state lighting (“SSL”) devices with improved contacts and associated methods of manufacturing are disclosed herein. In one embodiment, an SSL device includes an SSL structure having a first semiconductor material, a second semiconductor material spaced apart from the first semiconductor material, and an active region between the first and second semiconductor materials. The SSL device also includes a first contact on the first semiconductor material and a second contact on the second semiconductor material, where the first and second contacts define the current flow path through the SSL structure. The first or second contact is configured to provide a current density profile in the SSL structure based on a target current density profile.