GaN LED Interlayer Dislocation Density Management
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Solution Overview
Problem
Gallium nitride-based light emitting diodes face issues with high crystal defect density due to dislocations, which affect luminous efficiency and electro-static discharge characteristics, and the use of super-lattice interlayers increases process time and costs.
Innovation Solution
Incorporating interlayers with higher dislocation density between semiconductor layers to prevent dislocation transfer, allowing for a simpler process and improved electro-static discharge characteristics, while maintaining or reducing dislocation density in contact layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer layer and lower semiconductor layer are formed to reduce cracks and dislocations, then the occurrence of cracks or dislocations is reduced, but dislocation transfer to the active layer still occurs reducing luminous efficiency
Solution Approach 1:
An interlayer with high dislocation density is introduced between the lower semiconductor layer and the active layer to act as a mediator that blocks dislocation transfer. This interlayer absorbs dislocations through its high dislocation density, preventing them from reaching the active layer and maintaining low dislocation density in the active layer while allowing the buffer layer structure to remain in place
2Manufacturing precision
If an interlayer with super-lattice structure is used to prevent dislocation transfer, then dislocation transfer is blocked, but process time and fabrication costs are excessively increased
Solution Approach 1:
Instead of using a complex super-lattice structure, the invention changes the parameter of dislocation density in the interlayer to be high. This simple parameter change achieves dislocation transfer prevention without requiring the complex alternating layer structure, thereby reducing process time and fabrication costs while maintaining effective dislocation blocking
3Manufacturing precision
If the interlayer has higher dislocation density than adjacent layers, then dislocation transfer is prevented, but the interlayer itself contains more defects
Solution Approach 1:
The high dislocation density in the interlayer, which would normally be considered a defect, is converted into a beneficial feature. The dense dislocation structure acts as a barrier that absorbs and blocks dislocations from transferring between layers. The harm of having dislocations in the interlayer is transformed into the benefit of preventing dislocation transfer to critical layers like the 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
The approach effectively reduces dislocation transfer, enhances crystallinity, and improves electro-static discharge characteristics, while shortening the fabrication process time compared to super-lattice structures.
Implementation Method 1
the first interlayer has higher dislocation density than that of the buffer layer and has higher dislocation density than that of the first lower semiconductor layer
Data Source
AI summary
Disclosed herein are gallium nitride based light emitting diodes having interlayers with high dislocation density and a method of fabricating the same. The light emitting diode includes: a substrate; a buffer layer disposed on the substrate; an n-type contact layer disposed on the buffer; a p-type contact layer disposed on the n-type contact layer; an active layer interposed between the n-type contact layer and the p-type contact layer; a first lower semiconductor layer interposed between the buffer layer and the n-type contact layer; and a first interlayer interposed between the first lower semiconductor layer and the n-type contact layer, wherein the first interlayer has lower dislocation density than the buffer layer and higher dislocation density than the first lower semiconductor layer. This way, the interlayers with higher dislocation density prevent dislocations formed within the first lower semiconductor layer from being transferred to the n-type contact layer.