SSL Contact Layout for Uniform Current Density in LEDs
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Solution Overview
Problem
Conventional solid-state lighting (SSL) devices experience spatially non-uniform current densities, leading to reduced operating efficiency due to varying current flow through different regions of the GaN/InGaN multiple quantum wells, which can be attributed to the configuration and distribution of contacts.
Innovation Solution
The SSL devices incorporate a design with modulated contact resistance by using insulative and conductive materials with varying characteristics, such as different sizes and shapes of contact portions, and the inclusion of contact materials with distinct resistive properties to balance current densities across regions, achieved through techniques like chemical vapor deposition and patterning of these materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional contact configurations are used in SSL devices, then the device structure is simple, but the current density becomes spatially non-uniform leading to reduced operating efficiency
Solution Approach 1:
The patent applies local quality by varying the contact material properties and geometries in different regions of the SSL device. Specifically, different contact materials with different resistivities are used in different regions, and contact geometries are varied to achieve spatially non-uniform contact resistance that compensates for non-uniform current density, thereby improving operating efficiency while maintaining manufacturing feasibility
Solution Approach 2:
The patent changes physical parameters of the contact system, including contact material resistivity, contact area size, and contact geometry, to modulate the contact resistance spatially. By adjusting these parameters across different regions, the patent achieves more uniform current density distribution and improved operating efficiency without significantly complicating the manufacturing process
2Ease of manufacture
If contact materials with uniform properties are used, then the manufacturing process is simple, but the current density distribution becomes non-uniform across different regions
Solution Approach 1:
The patent implements local quality by using different contact materials with different electrical resistivities in different regions of the device. This allows the contact resistance to be tailored spatially, compensating for variations in current density and achieving more uniform current distribution across the active region, thereby improving manufacturing precision regarding current density uniformity
Solution Approach 2:
The patent introduces asymmetry in the contact system by using contact materials and geometries that are intentionally non-uniform across different regions. This asymmetric design compensates for the symmetric but non-uniform current density distribution that would result from uniform contacts, achieving more uniform current density without requiring complex manufacturing processes
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 more balanced and uniform current density profiles, enhancing the overall operating efficiency of the SSL devices by ensuring even current distribution across different regions.
Implementation Method 1
achieved through techniques like chemical vapor deposition and patterning of these materials
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.