Micro LED Diffusion Structure for Uniform Current Injection
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Solution Overview
Problem
Micro light-emitting diode chips experience low internal quantum efficiency due to high local current density and non-uniform current distribution, primarily because carriers recombine near the contact layer and semiconductor layer interface.
Innovation Solution
A micro light-emitting device structure is designed with a diffusion structure on the second-type semiconductor layer, which has lower conductivity than the semiconductor layer, forcing current to diffuse over a larger area, thereby increasing current density uniformity and improving internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carriers flow directly to the recombination region near the contact layer interface, then the current density becomes concentrated in a small area, but this results in high local current density and low internal quantum efficiency
Solution Approach 1:
The patent applies local quality by introducing a diffusion structure with specific conductivity properties at a particular location (second-type semiconductor layer) to create non-uniform current distribution that ultimately achieves uniform current density across the active layer, improving internal quantum efficiency
Solution Approach 2:
The diffusion structure acts as an intermediary element between the contact layer and the active layer, mediating the carrier flow to prevent direct concentration at the interface and instead distribute carriers uniformly across the active layer through controlled diffusion
2Reliability
If the diffusion structure has lower conductivity than the second-type semiconductor layer, then current diffusion is enhanced and uniformity improves, but this requires additional structural complexity
Solution Approach 1:
The patent changes the conductivity parameter of the diffusion structure to be lower than that of the second-type semiconductor layer, which controls the current diffusion behavior and achieves uniform current density distribution across the active layer, thereby improving internal quantum efficiency
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 effectively blocks direct carrier flow to the recombination region, enhancing current diffusion and resulting in improved internal quantum efficiency and display quality.
Implementation Method 1
A conductivity of the diffusion structure is less than a conductivity of the second-type semiconductor layer
Implementation Method 2
forcing the current to diffuse to a larger range, thereby increasing the uniformity of the current density
Data Source
AI summary
A micro light-emitting device includes an epitaxial structure, a first electrode, a second electrode, a first contact layer and a diffusion structure. The epitaxial structure includes a first-type semiconductor layer, an active layer and a second-type semiconductor layer stacked in sequence. The second-type semiconductor layer has an outer surface relatively away from the first-type semiconductor layer. The first and second electrodes are respectively disposed on the epitaxial structure and electrically connected to the first-type and the second-type semiconductor layers. The first contact layer is disposed between the first electrode and the first-type semiconductor layer. The diffusion structure is disposed on a side of the second-type semiconductor layer away from the first-type semiconductor layer. A conductivity of the diffusion structure is less than that of the second-type semiconductor layer. The outer surface of the second-type semiconductor layer exposes a lower surface of the diffusion structure away from the first-type semiconductor layer.